diff --git a/.coveragerc b/.coveragerc
index 05ec729aeff..2f76fa78d0f 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -810,6 +810,8 @@ omit =
     homeassistant/components/moehlenhoff_alpha2/binary_sensor.py
     homeassistant/components/moehlenhoff_alpha2/climate.py
     homeassistant/components/moehlenhoff_alpha2/sensor.py
+    homeassistant/components/monzo/__init__.py
+    homeassistant/components/monzo/api.py
     homeassistant/components/motion_blinds/__init__.py
     homeassistant/components/motion_blinds/coordinator.py
     homeassistant/components/motion_blinds/cover.py
diff --git a/.strict-typing b/.strict-typing
index 2589b90c998..36bfc6ffac9 100644
--- a/.strict-typing
+++ b/.strict-typing
@@ -300,6 +300,7 @@ homeassistant.components.minecraft_server.*
 homeassistant.components.mjpeg.*
 homeassistant.components.modbus.*
 homeassistant.components.modem_callerid.*
+homeassistant.components.monzo.*
 homeassistant.components.moon.*
 homeassistant.components.mopeka.*
 homeassistant.components.motionmount.*
diff --git a/CODEOWNERS b/CODEOWNERS
index 57f29f86a47..4920aeaf075 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -867,6 +867,8 @@ build.json @home-assistant/supervisor
 /tests/components/moehlenhoff_alpha2/ @j-a-n
 /homeassistant/components/monoprice/ @etsinko @OnFreund
 /tests/components/monoprice/ @etsinko @OnFreund
+/homeassistant/components/monzo/ @jakemartin-icl
+/tests/components/monzo/ @jakemartin-icl
 /homeassistant/components/moon/ @fabaff @frenck
 /tests/components/moon/ @fabaff @frenck
 /homeassistant/components/mopeka/ @bdraco
diff --git a/homeassistant/components/monzo/__init__.py b/homeassistant/components/monzo/__init__.py
new file mode 100644
index 00000000000..93fef56957e
--- /dev/null
+++ b/homeassistant/components/monzo/__init__.py
@@ -0,0 +1,68 @@
+"""The Monzo integration."""
+
+from __future__ import annotations
+
+from datetime import timedelta
+import logging
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import Platform
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import aiohttp_client, config_entry_oauth2_flow
+from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
+
+from .api import AuthenticatedMonzoAPI
+from .const import DOMAIN
+from .data import MonzoData, MonzoSensorData
+
+PLATFORMS: list[Platform] = [Platform.SENSOR]
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Set up Monzo from a config entry."""
+    implementation = (
+        await config_entry_oauth2_flow.async_get_config_entry_implementation(
+            hass, entry
+        )
+    )
+
+    async def async_get_monzo_api_data() -> MonzoSensorData:
+        monzo_data: MonzoData = hass.data[DOMAIN][entry.entry_id]
+        accounts = await external_api.user_account.accounts()
+        pots = await external_api.user_account.pots()
+        monzo_data.accounts = accounts
+        monzo_data.pots = pots
+        return MonzoSensorData(accounts=accounts, pots=pots)
+
+    session = config_entry_oauth2_flow.OAuth2Session(hass, entry, implementation)
+
+    external_api = AuthenticatedMonzoAPI(
+        aiohttp_client.async_get_clientsession(hass), session
+    )
+
+    coordinator = DataUpdateCoordinator(
+        hass,
+        logging.getLogger(__name__),
+        name=DOMAIN,
+        update_method=async_get_monzo_api_data,
+        update_interval=timedelta(minutes=1),
+    )
+    hass.data.setdefault(DOMAIN, {})
+    hass.data[DOMAIN][entry.entry_id] = MonzoData(external_api, coordinator)
+
+    await coordinator.async_config_entry_first_refresh()
+    await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
+
+    return True
+
+
+async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Unload a config entry."""
+    data = hass.data[DOMAIN]
+
+    unload_ok = await hass.config_entries.async_unload_platforms(entry, PLATFORMS)
+
+    if unload_ok and entry.entry_id in data:
+        data.pop(entry.entry_id)
+
+    return unload_ok
diff --git a/homeassistant/components/monzo/api.py b/homeassistant/components/monzo/api.py
new file mode 100644
index 00000000000..6862564d343
--- /dev/null
+++ b/homeassistant/components/monzo/api.py
@@ -0,0 +1,26 @@
+"""API for Monzo bound to Home Assistant OAuth."""
+
+from aiohttp import ClientSession
+from monzopy import AbstractMonzoApi
+
+from homeassistant.helpers import config_entry_oauth2_flow
+
+
+class AuthenticatedMonzoAPI(AbstractMonzoApi):
+    """A Monzo API instance with authentication tied to an OAuth2 based config entry."""
+
+    def __init__(
+        self,
+        websession: ClientSession,
+        oauth_session: config_entry_oauth2_flow.OAuth2Session,
+    ) -> None:
+        """Initialize Monzo auth."""
+        super().__init__(websession)
+        self._oauth_session = oauth_session
+
+    async def async_get_access_token(self) -> str:
+        """Return a valid access token."""
+        if not self._oauth_session.valid_token:
+            await self._oauth_session.async_ensure_token_valid()
+
+        return str(self._oauth_session.token["access_token"])
diff --git a/homeassistant/components/monzo/application_credentials.py b/homeassistant/components/monzo/application_credentials.py
new file mode 100644
index 00000000000..f040c150853
--- /dev/null
+++ b/homeassistant/components/monzo/application_credentials.py
@@ -0,0 +1,15 @@
+"""application_credentials platform the Monzo integration."""
+
+from homeassistant.components.application_credentials import AuthorizationServer
+from homeassistant.core import HomeAssistant
+
+OAUTH2_AUTHORIZE = "https://auth.monzo.com"
+OAUTH2_TOKEN = "https://api.monzo.com/oauth2/token"
+
+
+async def async_get_authorization_server(hass: HomeAssistant) -> AuthorizationServer:
+    """Return authorization server."""
+    return AuthorizationServer(
+        authorize_url=OAUTH2_AUTHORIZE,
+        token_url=OAUTH2_TOKEN,
+    )
diff --git a/homeassistant/components/monzo/config_flow.py b/homeassistant/components/monzo/config_flow.py
new file mode 100644
index 00000000000..1d5bc3147b1
--- /dev/null
+++ b/homeassistant/components/monzo/config_flow.py
@@ -0,0 +1,52 @@
+"""Config flow for Monzo."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+import voluptuous as vol
+
+from homeassistant.config_entries import ConfigFlowResult
+from homeassistant.const import CONF_TOKEN
+from homeassistant.helpers import config_entry_oauth2_flow
+
+from .const import DOMAIN
+
+
+class MonzoFlowHandler(
+    config_entry_oauth2_flow.AbstractOAuth2FlowHandler, domain=DOMAIN
+):
+    """Handle a config flow."""
+
+    DOMAIN = DOMAIN
+
+    oauth_data: dict[str, Any]
+
+    @property
+    def logger(self) -> logging.Logger:
+        """Return logger."""
+        return logging.getLogger(__name__)
+
+    async def async_step_await_approval_confirmation(
+        self, user_input: dict[str, Any] | None = None
+    ) -> ConfigFlowResult:
+        """Wait for the user to confirm in-app approval."""
+        if user_input is not None:
+            return self.async_create_entry(title=DOMAIN, data={**self.oauth_data})
+
+        data_schema = vol.Schema({vol.Required("confirm"): bool})
+
+        return self.async_show_form(
+            step_id="await_approval_confirmation", data_schema=data_schema
+        )
+
+    async def async_oauth_create_entry(self, data: dict[str, Any]) -> ConfigFlowResult:
+        """Create an entry for the flow."""
+        user_id = str(data[CONF_TOKEN]["user_id"])
+        await self.async_set_unique_id(user_id)
+        self._abort_if_unique_id_configured()
+
+        self.oauth_data = data
+
+        return await self.async_step_await_approval_confirmation()
diff --git a/homeassistant/components/monzo/const.py b/homeassistant/components/monzo/const.py
new file mode 100644
index 00000000000..619daf120f7
--- /dev/null
+++ b/homeassistant/components/monzo/const.py
@@ -0,0 +1,3 @@
+"""Constants for the Monzo integration."""
+
+DOMAIN = "monzo"
diff --git a/homeassistant/components/monzo/data.py b/homeassistant/components/monzo/data.py
new file mode 100644
index 00000000000..c4dd2564c21
--- /dev/null
+++ b/homeassistant/components/monzo/data.py
@@ -0,0 +1,24 @@
+"""Dataclass for Monzo data."""
+
+from dataclasses import dataclass, field
+from typing import Any
+
+from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
+
+from .api import AuthenticatedMonzoAPI
+
+
+@dataclass(kw_only=True)
+class MonzoSensorData:
+    """A dataclass for holding sensor data returned by the DataUpdateCoordinator."""
+
+    accounts: list[dict[str, Any]] = field(default_factory=list)
+    pots: list[dict[str, Any]] = field(default_factory=list)
+
+
+@dataclass
+class MonzoData(MonzoSensorData):
+    """A dataclass for holding data stored in hass.data."""
+
+    external_api: AuthenticatedMonzoAPI
+    coordinator: DataUpdateCoordinator[MonzoSensorData]
diff --git a/homeassistant/components/monzo/entity.py b/homeassistant/components/monzo/entity.py
new file mode 100644
index 00000000000..043c06eece0
--- /dev/null
+++ b/homeassistant/components/monzo/entity.py
@@ -0,0 +1,47 @@
+"""Base entity for Monzo."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from typing import Any
+
+from homeassistant.helpers.device_registry import DeviceEntryType, DeviceInfo
+from homeassistant.helpers.update_coordinator import (
+    CoordinatorEntity,
+    DataUpdateCoordinator,
+)
+
+from .const import DOMAIN
+from .data import MonzoSensorData
+
+
+class MonzoBaseEntity(CoordinatorEntity[DataUpdateCoordinator[MonzoSensorData]]):
+    """Common base for Monzo entities."""
+
+    _attr_attribution = "Data provided by Monzo"
+    _attr_has_entity_name = True
+
+    def __init__(
+        self,
+        coordinator: DataUpdateCoordinator[MonzoSensorData],
+        index: int,
+        device_model: str,
+        data_accessor: Callable[[MonzoSensorData], list[dict[str, Any]]],
+    ) -> None:
+        """Initialize sensor."""
+        super().__init__(coordinator)
+        self.index = index
+        self._data_accessor = data_accessor
+
+        self._attr_device_info = DeviceInfo(
+            entry_type=DeviceEntryType.SERVICE,
+            identifiers={(DOMAIN, str(self.data["id"]))},
+            manufacturer="Monzo",
+            model=device_model,
+            name=self.data["name"],
+        )
+
+    @property
+    def data(self) -> dict[str, Any]:
+        """Shortcut to access coordinator data for the entity."""
+        return self._data_accessor(self.coordinator.data)[self.index]
diff --git a/homeassistant/components/monzo/manifest.json b/homeassistant/components/monzo/manifest.json
new file mode 100644
index 00000000000..8dd084e2b95
--- /dev/null
+++ b/homeassistant/components/monzo/manifest.json
@@ -0,0 +1,10 @@
+{
+  "domain": "monzo",
+  "name": "Monzo",
+  "codeowners": ["@jakemartin-icl"],
+  "config_flow": true,
+  "dependencies": ["application_credentials"],
+  "documentation": "https://www.home-assistant.io/integrations/monzo",
+  "iot_class": "cloud_polling",
+  "requirements": ["monzopy==1.1.0"]
+}
diff --git a/homeassistant/components/monzo/sensor.py b/homeassistant/components/monzo/sensor.py
new file mode 100644
index 00000000000..be13608ca3b
--- /dev/null
+++ b/homeassistant/components/monzo/sensor.py
@@ -0,0 +1,123 @@
+"""Platform for sensor integration."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from dataclasses import dataclass
+from typing import Any
+
+from homeassistant.components.sensor import (
+    SensorDeviceClass,
+    SensorEntity,
+    SensorEntityDescription,
+)
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers.entity_platform import AddEntitiesCallback
+from homeassistant.helpers.typing import StateType
+from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
+
+from .const import DOMAIN
+from .data import MonzoSensorData
+from .entity import MonzoBaseEntity
+
+
+@dataclass(frozen=True, kw_only=True)
+class MonzoSensorEntityDescription(SensorEntityDescription):
+    """Describes Monzo sensor entity."""
+
+    value_fn: Callable[[dict[str, Any]], StateType]
+
+
+ACCOUNT_SENSORS = (
+    MonzoSensorEntityDescription(
+        key="balance",
+        translation_key="balance",
+        value_fn=lambda data: data["balance"]["balance"] / 100,
+        device_class=SensorDeviceClass.MONETARY,
+        native_unit_of_measurement="GBP",
+        suggested_display_precision=2,
+    ),
+    MonzoSensorEntityDescription(
+        key="total_balance",
+        translation_key="total_balance",
+        value_fn=lambda data: data["balance"]["total_balance"] / 100,
+        device_class=SensorDeviceClass.MONETARY,
+        native_unit_of_measurement="GBP",
+        suggested_display_precision=2,
+    ),
+)
+
+POT_SENSORS = (
+    MonzoSensorEntityDescription(
+        key="pot_balance",
+        translation_key="pot_balance",
+        value_fn=lambda data: data["balance"] / 100,
+        device_class=SensorDeviceClass.MONETARY,
+        native_unit_of_measurement="GBP",
+        suggested_display_precision=2,
+    ),
+)
+
+MODEL_POT = "Pot"
+
+
+async def async_setup_entry(
+    hass: HomeAssistant,
+    config_entry: ConfigEntry,
+    async_add_entities: AddEntitiesCallback,
+) -> None:
+    """Defer sensor setup to the shared sensor module."""
+    coordinator = hass.data[DOMAIN][config_entry.entry_id].coordinator
+
+    accounts = [
+        MonzoSensor(
+            coordinator,
+            entity_description,
+            index,
+            account["name"],
+            lambda x: x.accounts,
+        )
+        for entity_description in ACCOUNT_SENSORS
+        for index, account in enumerate(
+            hass.data[DOMAIN][config_entry.entry_id].accounts
+        )
+    ]
+
+    pots = [
+        MonzoSensor(coordinator, entity_description, index, MODEL_POT, lambda x: x.pots)
+        for entity_description in POT_SENSORS
+        for index, _pot in enumerate(hass.data[DOMAIN][config_entry.entry_id].pots)
+    ]
+
+    async_add_entities(accounts + pots)
+
+
+class MonzoSensor(MonzoBaseEntity, SensorEntity):
+    """Represents a Monzo sensor."""
+
+    entity_description: MonzoSensorEntityDescription
+
+    def __init__(
+        self,
+        coordinator: DataUpdateCoordinator[MonzoSensorData],
+        entity_description: MonzoSensorEntityDescription,
+        index: int,
+        device_model: str,
+        data_accessor: Callable[[MonzoSensorData], list[dict[str, Any]]],
+    ) -> None:
+        """Initialize the sensor."""
+        super().__init__(coordinator, index, device_model, data_accessor)
+        self.entity_description = entity_description
+        self._attr_unique_id = f"{self.data['id']}_{entity_description.key}"
+
+    @property
+    def native_value(self) -> StateType:
+        """Return the state."""
+
+        try:
+            state = self.entity_description.value_fn(self.data)
+        except (KeyError, ValueError):
+            return None
+
+        return state
diff --git a/homeassistant/components/monzo/strings.json b/homeassistant/components/monzo/strings.json
new file mode 100644
index 00000000000..963c02232f1
--- /dev/null
+++ b/homeassistant/components/monzo/strings.json
@@ -0,0 +1,41 @@
+{
+  "config": {
+    "step": {
+      "pick_implementation": {
+        "title": "[%key:common::config_flow::title::oauth2_pick_implementation%]"
+      },
+      "await_approval_confirmation": {
+        "title": "Confirm in Monzo app",
+        "description": "Before proceeding, open your Monzo app and approve the request from Home Assistant.",
+        "data": {
+          "confirm": "I've approved"
+        }
+      }
+    },
+    "abort": {
+      "already_configured": "[%key:common::config_flow::abort::already_configured_account%]",
+      "already_in_progress": "[%key:common::config_flow::abort::already_in_progress%]",
+      "oauth_error": "[%key:common::config_flow::abort::oauth2_error%]",
+      "missing_configuration": "[%key:common::config_flow::abort::oauth2_missing_configuration%]",
+      "authorize_url_timeout": "[%key:common::config_flow::abort::oauth2_authorize_url_timeout%]",
+      "no_url_available": "[%key:common::config_flow::abort::oauth2_no_url_available%]",
+      "user_rejected_authorize": "[%key:common::config_flow::abort::oauth2_user_rejected_authorize%]"
+    },
+    "create_entry": {
+      "default": "[%key:common::config_flow::create_entry::authenticated%]"
+    }
+  },
+  "entity": {
+    "sensor": {
+      "balance": {
+        "name": "Balance"
+      },
+      "total_balance": {
+        "name": "Total Balance"
+      },
+      "pot_balance": {
+        "name": "Balance"
+      }
+    }
+  }
+}
diff --git a/homeassistant/generated/application_credentials.py b/homeassistant/generated/application_credentials.py
index 15ae2e369de..c576f242e30 100644
--- a/homeassistant/generated/application_credentials.py
+++ b/homeassistant/generated/application_credentials.py
@@ -17,6 +17,7 @@ APPLICATION_CREDENTIALS = [
     "lametric",
     "lyric",
     "microbees",
+    "monzo",
     "myuplink",
     "neato",
     "nest",
diff --git a/homeassistant/generated/config_flows.py b/homeassistant/generated/config_flows.py
index 1396a161bef..a9a387de473 100644
--- a/homeassistant/generated/config_flows.py
+++ b/homeassistant/generated/config_flows.py
@@ -331,6 +331,7 @@ FLOWS = {
         "modern_forms",
         "moehlenhoff_alpha2",
         "monoprice",
+        "monzo",
         "moon",
         "mopeka",
         "motion_blinds",
diff --git a/homeassistant/generated/integrations.json b/homeassistant/generated/integrations.json
index c5e7a842c45..ceb3d9955d4 100644
--- a/homeassistant/generated/integrations.json
+++ b/homeassistant/generated/integrations.json
@@ -3739,6 +3739,12 @@
       "config_flow": true,
       "iot_class": "local_polling"
     },
+    "monzo": {
+      "name": "Monzo",
+      "integration_type": "hub",
+      "config_flow": true,
+      "iot_class": "cloud_polling"
+    },
     "moon": {
       "integration_type": "service",
       "config_flow": true,
diff --git a/mypy.ini b/mypy.ini
index becf1b7751d..6da57f22252 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -2762,6 +2762,16 @@ disallow_untyped_defs = true
 warn_return_any = true
 warn_unreachable = true
 
+[mypy-homeassistant.components.monzo.*]
+check_untyped_defs = true
+disallow_incomplete_defs = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
+disallow_untyped_defs = true
+warn_return_any = true
+warn_unreachable = true
+
 [mypy-homeassistant.components.moon.*]
 check_untyped_defs = true
 disallow_incomplete_defs = true
diff --git a/requirements_all.txt b/requirements_all.txt
index 71772b13477..3689912e8b4 100644
--- a/requirements_all.txt
+++ b/requirements_all.txt
@@ -1325,6 +1325,9 @@ moat-ble==0.1.1
 # homeassistant.components.moehlenhoff_alpha2
 moehlenhoff-alpha2==1.3.0
 
+# homeassistant.components.monzo
+monzopy==1.1.0
+
 # homeassistant.components.mopeka
 mopeka-iot-ble==0.7.0
 
diff --git a/requirements_test_all.txt b/requirements_test_all.txt
index ad225de6353..572ef59ebdd 100644
--- a/requirements_test_all.txt
+++ b/requirements_test_all.txt
@@ -1067,6 +1067,9 @@ moat-ble==0.1.1
 # homeassistant.components.moehlenhoff_alpha2
 moehlenhoff-alpha2==1.3.0
 
+# homeassistant.components.monzo
+monzopy==1.1.0
+
 # homeassistant.components.mopeka
 mopeka-iot-ble==0.7.0
 
diff --git a/tests/components/monzo/__init__.py b/tests/components/monzo/__init__.py
new file mode 100644
index 00000000000..db732171521
--- /dev/null
+++ b/tests/components/monzo/__init__.py
@@ -0,0 +1,12 @@
+"""Tests for the Monzo integration."""
+
+from homeassistant.core import HomeAssistant
+
+from tests.common import MockConfigEntry
+
+
+async def setup_integration(hass: HomeAssistant, config_entry: MockConfigEntry) -> None:
+    """Fixture for setting up the component."""
+    config_entry.add_to_hass(hass)
+
+    await hass.config_entries.async_setup(config_entry.entry_id)
diff --git a/tests/components/monzo/conftest.py b/tests/components/monzo/conftest.py
new file mode 100644
index 00000000000..451fd6b409d
--- /dev/null
+++ b/tests/components/monzo/conftest.py
@@ -0,0 +1,125 @@
+"""Fixtures for tests."""
+
+import time
+from unittest.mock import AsyncMock, patch
+
+from monzopy.monzopy import UserAccount
+import pytest
+
+from homeassistant.components.application_credentials import (
+    ClientCredential,
+    async_import_client_credential,
+)
+from homeassistant.components.monzo.api import AuthenticatedMonzoAPI
+from homeassistant.components.monzo.const import DOMAIN
+from homeassistant.core import HomeAssistant
+from homeassistant.setup import async_setup_component
+
+from tests.common import MockConfigEntry
+
+CLIENT_ID = "1234"
+CLIENT_SECRET = "5678"
+TEST_ACCOUNTS = [
+    {
+        "id": "acc_curr",
+        "name": "Current Account",
+        "type": "uk_retail",
+        "balance": {"balance": 123, "total_balance": 321},
+    },
+    {
+        "id": "acc_flex",
+        "name": "Flex",
+        "type": "uk_monzo_flex",
+        "balance": {"balance": 123, "total_balance": 321},
+    },
+]
+TEST_POTS = [
+    {
+        "id": "pot_savings",
+        "name": "Savings",
+        "style": "savings",
+        "balance": 134578,
+        "currency": "GBP",
+        "type": "instant_access",
+    }
+]
+TITLE = "jake"
+USER_ID = 12345
+
+
+@pytest.fixture(autouse=True)
+async def setup_credentials(hass: HomeAssistant) -> None:
+    """Fixture to setup credentials."""
+    assert await async_setup_component(hass, "application_credentials", {})
+    await async_import_client_credential(
+        hass,
+        DOMAIN,
+        ClientCredential(CLIENT_ID, CLIENT_SECRET, DOMAIN),
+    )
+
+
+@pytest.fixture(name="expires_at")
+def mock_expires_at() -> int:
+    """Fixture to set the oauth token expiration time."""
+    return time.time() + 3600
+
+
+@pytest.fixture
+def polling_config_entry(expires_at: int) -> MockConfigEntry:
+    """Create Monzo entry in Home Assistant."""
+    return MockConfigEntry(
+        domain=DOMAIN,
+        title=TITLE,
+        unique_id=str(USER_ID),
+        data={
+            "auth_implementation": DOMAIN,
+            "token": {
+                "status": 0,
+                "userid": str(USER_ID),
+                "access_token": "mock-access-token",
+                "refresh_token": "mock-refresh-token",
+                "expires_in": 60,
+                "expires_at": time.time() + 1000,
+            },
+            "profile": TITLE,
+        },
+    )
+
+
+@pytest.fixture(name="basic_monzo")
+def mock_basic_monzo():
+    """Mock monzo with one pot."""
+
+    mock = AsyncMock(spec=AuthenticatedMonzoAPI)
+    mock_user_account = AsyncMock(spec=UserAccount)
+
+    mock_user_account.accounts.return_value = []
+
+    mock_user_account.pots.return_value = TEST_POTS
+
+    mock.user_account = mock_user_account
+
+    with patch(
+        "homeassistant.components.monzo.AuthenticatedMonzoAPI",
+        return_value=mock,
+    ):
+        yield mock
+
+
+@pytest.fixture(name="monzo")
+def mock_monzo():
+    """Mock monzo."""
+
+    mock = AsyncMock(spec=AuthenticatedMonzoAPI)
+    mock_user_account = AsyncMock(spec=UserAccount)
+
+    mock_user_account.accounts.return_value = TEST_ACCOUNTS
+    mock_user_account.pots.return_value = TEST_POTS
+
+    mock.user_account = mock_user_account
+
+    with patch(
+        "homeassistant.components.monzo.AuthenticatedMonzoAPI",
+        return_value=mock,
+    ):
+        yield mock
diff --git a/tests/components/monzo/snapshots/test_sensor.ambr b/tests/components/monzo/snapshots/test_sensor.ambr
new file mode 100644
index 00000000000..8a6b39768b0
--- /dev/null
+++ b/tests/components/monzo/snapshots/test_sensor.ambr
@@ -0,0 +1,65 @@
+# serializer version: 1
+# name: test_all_entities
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'attribution': 'Data provided by Monzo',
+      'device_class': 'monetary',
+      'friendly_name': 'Current Account Balance',
+      'unit_of_measurement': 'GBP',
+    }),
+    'context': <ANY>,
+    'entity_id': 'sensor.current_account_balance',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': '1.23',
+  })
+# ---
+# name: test_all_entities.1
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'attribution': 'Data provided by Monzo',
+      'device_class': 'monetary',
+      'friendly_name': 'Current Account Total Balance',
+      'unit_of_measurement': 'GBP',
+    }),
+    'context': <ANY>,
+    'entity_id': 'sensor.current_account_total_balance',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': '3.21',
+  })
+# ---
+# name: test_all_entities.2
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'attribution': 'Data provided by Monzo',
+      'device_class': 'monetary',
+      'friendly_name': 'Flex Balance',
+      'unit_of_measurement': 'GBP',
+    }),
+    'context': <ANY>,
+    'entity_id': 'sensor.flex_balance',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': '1.23',
+  })
+# ---
+# name: test_all_entities.3
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'attribution': 'Data provided by Monzo',
+      'device_class': 'monetary',
+      'friendly_name': 'Flex Total Balance',
+      'unit_of_measurement': 'GBP',
+    }),
+    'context': <ANY>,
+    'entity_id': 'sensor.flex_total_balance',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': '3.21',
+  })
+# ---
diff --git a/tests/components/monzo/test_config_flow.py b/tests/components/monzo/test_config_flow.py
new file mode 100644
index 00000000000..dc3138e6a0d
--- /dev/null
+++ b/tests/components/monzo/test_config_flow.py
@@ -0,0 +1,138 @@
+"""Tests for config flow."""
+
+from unittest.mock import AsyncMock, patch
+
+from homeassistant.components.monzo.application_credentials import (
+    OAUTH2_AUTHORIZE,
+    OAUTH2_TOKEN,
+)
+from homeassistant.components.monzo.const import DOMAIN
+from homeassistant.config_entries import SOURCE_USER
+from homeassistant.core import HomeAssistant
+from homeassistant.data_entry_flow import FlowResultType
+from homeassistant.helpers import config_entry_oauth2_flow
+
+from . import setup_integration
+from .conftest import CLIENT_ID, USER_ID
+
+from tests.common import MockConfigEntry
+from tests.test_util.aiohttp import AiohttpClientMocker
+from tests.typing import ClientSessionGenerator
+
+
+async def test_full_flow(
+    hass: HomeAssistant,
+    hass_client_no_auth: ClientSessionGenerator,
+    current_request_with_host: None,
+    aioclient_mock: AiohttpClientMocker,
+) -> None:
+    """Check full flow."""
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": SOURCE_USER}
+    )
+    state = config_entry_oauth2_flow._encode_jwt(
+        hass,
+        {
+            "flow_id": result["flow_id"],
+            "redirect_uri": "https://example.com/auth/external/callback",
+        },
+    )
+
+    assert result["type"] == FlowResultType.EXTERNAL_STEP
+    assert result["url"] == (
+        f"{OAUTH2_AUTHORIZE}/?"
+        f"response_type=code&client_id={CLIENT_ID}&"
+        "redirect_uri=https://example.com/auth/external/callback&"
+        f"state={state}"
+    )
+
+    client = await hass_client_no_auth()
+    resp = await client.get(f"/auth/external/callback?code=abcd&state={state}")
+    assert resp.status == 200
+    assert resp.headers["content-type"] == "text/html; charset=utf-8"
+
+    aioclient_mock.clear_requests()
+    aioclient_mock.post(
+        OAUTH2_TOKEN,
+        json={
+            "refresh_token": "mock-refresh-token",
+            "access_token": "mock-access-token",
+            "type": "Bearer",
+            "expires_in": 60,
+            "user_id": 600,
+        },
+    )
+    with patch(
+        "homeassistant.components.monzo.async_setup_entry", return_value=True
+    ) as mock_setup:
+        result = await hass.config_entries.flow.async_configure(result["flow_id"])
+
+        assert len(mock_setup.mock_calls) == 0
+
+        assert result["type"] == FlowResultType.FORM
+        assert result["step_id"] == "await_approval_confirmation"
+
+        result = await hass.config_entries.flow.async_configure(
+            result["flow_id"], user_input={"confirm": True}
+        )
+
+    assert len(hass.config_entries.async_entries(DOMAIN)) == 1
+    assert len(mock_setup.mock_calls) == 1
+
+    assert result["type"] == FlowResultType.CREATE_ENTRY
+    assert result["title"] == DOMAIN
+    assert "result" in result
+    assert result["result"].unique_id == "600"
+    assert "token" in result["result"].data
+    assert result["result"].data["token"]["access_token"] == "mock-access-token"
+    assert result["result"].data["token"]["refresh_token"] == "mock-refresh-token"
+
+
+async def test_config_non_unique_profile(
+    hass: HomeAssistant,
+    hass_client_no_auth: ClientSessionGenerator,
+    current_request_with_host: None,
+    monzo: AsyncMock,
+    polling_config_entry: MockConfigEntry,
+    aioclient_mock: AiohttpClientMocker,
+) -> None:
+    """Test setup a non-unique profile."""
+    await setup_integration(hass, polling_config_entry)
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": SOURCE_USER}
+    )
+    state = config_entry_oauth2_flow._encode_jwt(
+        hass,
+        {
+            "flow_id": result["flow_id"],
+            "redirect_uri": "https://example.com/auth/external/callback",
+        },
+    )
+
+    assert result["type"] == FlowResultType.EXTERNAL_STEP
+    assert result["url"] == (
+        f"{OAUTH2_AUTHORIZE}/?"
+        f"response_type=code&client_id={CLIENT_ID}&"
+        "redirect_uri=https://example.com/auth/external/callback&"
+        f"state={state}"
+    )
+
+    client = await hass_client_no_auth()
+    resp = await client.get(f"/auth/external/callback?code=abcd&state={state}")
+    assert resp.status == 200
+    assert resp.headers["content-type"] == "text/html; charset=utf-8"
+
+    aioclient_mock.clear_requests()
+    aioclient_mock.post(
+        OAUTH2_TOKEN,
+        json={
+            "refresh_token": "mock-refresh-token",
+            "access_token": "mock-access-token",
+            "type": "Bearer",
+            "expires_in": 60,
+            "user_id": str(USER_ID),
+        },
+    )
+    result = await hass.config_entries.flow.async_configure(result["flow_id"])
+    assert result["type"] == FlowResultType.ABORT
+    assert result["reason"] == "already_configured"
diff --git a/tests/components/monzo/test_sensor.py b/tests/components/monzo/test_sensor.py
new file mode 100644
index 00000000000..6b5ca4a2349
--- /dev/null
+++ b/tests/components/monzo/test_sensor.py
@@ -0,0 +1,141 @@
+"""Tests for the Monzo component."""
+
+from datetime import timedelta
+from typing import Any
+from unittest.mock import AsyncMock
+
+from freezegun.api import FrozenDateTimeFactory
+import pytest
+from syrupy import SnapshotAssertion
+
+from homeassistant.components.monzo.const import DOMAIN
+from homeassistant.components.monzo.sensor import (
+    ACCOUNT_SENSORS,
+    POT_SENSORS,
+    MonzoSensorEntityDescription,
+)
+from homeassistant.components.sensor import DOMAIN as SENSOR_DOMAIN
+from homeassistant.const import STATE_UNAVAILABLE
+from homeassistant.core import HomeAssistant, State
+from homeassistant.helpers import entity_registry as er
+from homeassistant.helpers.entity_registry import EntityRegistry
+
+from . import setup_integration
+from .conftest import TEST_ACCOUNTS, TEST_POTS
+
+from tests.common import MockConfigEntry, async_fire_time_changed
+from tests.typing import ClientSessionGenerator
+
+EXPECTED_VALUE_GETTERS = {
+    "balance": lambda x: x["balance"]["balance"] / 100,
+    "total_balance": lambda x: x["balance"]["total_balance"] / 100,
+    "pot_balance": lambda x: x["balance"] / 100,
+}
+
+
+async def async_get_entity_id(
+    hass: HomeAssistant,
+    acc_id: str,
+    description: MonzoSensorEntityDescription,
+) -> str | None:
+    """Get an entity id for a user's attribute."""
+    entity_registry = er.async_get(hass)
+    unique_id = f"{acc_id}_{description.key}"
+
+    return entity_registry.async_get_entity_id(SENSOR_DOMAIN, DOMAIN, unique_id)
+
+
+def async_assert_state_equals(
+    entity_id: str,
+    state_obj: State,
+    expected: Any,
+    description: MonzoSensorEntityDescription,
+) -> None:
+    """Assert at given state matches what is expected."""
+    assert state_obj, f"Expected entity {entity_id} to exist but it did not"
+
+    assert state_obj.state == str(expected), (
+        f"Expected {expected} but was {state_obj.state} "
+        f"for measure {description.name}, {entity_id}"
+    )
+
+
+@pytest.mark.usefixtures("entity_registry_enabled_by_default")
+async def test_sensor_default_enabled_entities(
+    hass: HomeAssistant,
+    monzo: AsyncMock,
+    polling_config_entry: MockConfigEntry,
+    hass_client_no_auth: ClientSessionGenerator,
+) -> None:
+    """Test entities enabled by default."""
+    await setup_integration(hass, polling_config_entry)
+    entity_registry: EntityRegistry = er.async_get(hass)
+
+    for acc in TEST_ACCOUNTS:
+        for sensor_description in ACCOUNT_SENSORS:
+            entity_id = await async_get_entity_id(hass, acc["id"], sensor_description)
+            assert entity_id
+            assert entity_registry.async_is_registered(entity_id)
+
+            state = hass.states.get(entity_id)
+            assert state.state == str(
+                EXPECTED_VALUE_GETTERS[sensor_description.key](acc)
+            )
+
+
+@pytest.mark.usefixtures("entity_registry_enabled_by_default")
+async def test_unavailable_entity(
+    hass: HomeAssistant,
+    basic_monzo: AsyncMock,
+    polling_config_entry: MockConfigEntry,
+    hass_client_no_auth: ClientSessionGenerator,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test entities enabled by default."""
+    await setup_integration(hass, polling_config_entry)
+    basic_monzo.user_account.pots.return_value = [{"id": "pot_savings"}]
+    freezer.tick(timedelta(minutes=100))
+    async_fire_time_changed(hass)
+    await hass.async_block_till_done()
+    entity_id = await async_get_entity_id(hass, TEST_POTS[0]["id"], POT_SENSORS[0])
+    state = hass.states.get(entity_id)
+    assert state.state == "unknown"
+
+
+@pytest.mark.usefixtures("entity_registry_enabled_by_default")
+async def test_all_entities(
+    hass: HomeAssistant,
+    snapshot: SnapshotAssertion,
+    monzo: AsyncMock,
+    polling_config_entry: MockConfigEntry,
+) -> None:
+    """Test all entities."""
+    await setup_integration(hass, polling_config_entry)
+
+    for acc in TEST_ACCOUNTS:
+        for sensor in ACCOUNT_SENSORS:
+            entity_id = await async_get_entity_id(hass, acc["id"], sensor)
+            assert hass.states.get(entity_id) == snapshot
+
+
+async def test_update_failed(
+    hass: HomeAssistant,
+    snapshot: SnapshotAssertion,
+    monzo: AsyncMock,
+    polling_config_entry: MockConfigEntry,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test all entities."""
+    await setup_integration(hass, polling_config_entry)
+
+    monzo.user_account.accounts.side_effect = Exception
+    freezer.tick(timedelta(minutes=10))
+    async_fire_time_changed(hass)
+    await hass.async_block_till_done()
+
+    entity_id = await async_get_entity_id(
+        hass, TEST_ACCOUNTS[0]["id"], ACCOUNT_SENSORS[0]
+    )
+    state = hass.states.get(entity_id)
+    assert state is not None
+    assert state.state == STATE_UNAVAILABLE