diff --git a/homeassistant/components/notion/__init__.py b/homeassistant/components/notion/__init__.py
index 294d93a30e2..6fff031ae25 100644
--- a/homeassistant/components/notion/__init__.py
+++ b/homeassistant/components/notion/__init__.py
@@ -208,7 +208,7 @@ class NotionEntity(CoordinatorEntity):
         raise NotImplementedError
 
     @callback
-    def _handle_coordinator_update(self):
+    def _handle_coordinator_update(self) -> None:
         """Respond to a DataUpdateCoordinator update."""
         if self._task_id in self.coordinator.data["tasks"]:
             self.hass.async_create_task(self._async_update_bridge_id())
@@ -216,7 +216,7 @@ class NotionEntity(CoordinatorEntity):
 
         self.async_write_ha_state()
 
-    async def async_added_to_hass(self):
+    async def async_added_to_hass(self) -> None:
         """Handle entity which will be added."""
         await super().async_added_to_hass()
         self._async_update_from_latest_data()
diff --git a/homeassistant/components/notion/binary_sensor.py b/homeassistant/components/notion/binary_sensor.py
index 2604e2bdf58..d3b1d8e3ef2 100644
--- a/homeassistant/components/notion/binary_sensor.py
+++ b/homeassistant/components/notion/binary_sensor.py
@@ -44,7 +44,7 @@ BINARY_SENSOR_TYPES = {
 
 async def async_setup_entry(
     hass: HomeAssistant, entry: ConfigEntry, async_add_entities: AddEntitiesCallback
-):
+) -> None:
     """Set up Notion sensors based on a config entry."""
     coordinator = hass.data[DOMAIN][DATA_COORDINATOR][entry.entry_id]
 
diff --git a/homeassistant/components/notion/config_flow.py b/homeassistant/components/notion/config_flow.py
index 13386a67c02..4b654e4366e 100644
--- a/homeassistant/components/notion/config_flow.py
+++ b/homeassistant/components/notion/config_flow.py
@@ -1,10 +1,13 @@
 """Config flow to configure the Notion integration."""
+from __future__ import annotations
+
 from aionotion import async_get_client
 from aionotion.errors import NotionError
 import voluptuous as vol
 
 from homeassistant import config_entries
 from homeassistant.const import CONF_PASSWORD, CONF_USERNAME
+from homeassistant.data_entry_flow import FlowResult
 from homeassistant.helpers import aiohttp_client
 
 from .const import DOMAIN
@@ -15,19 +18,21 @@ class NotionFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
 
     VERSION = 1
 
-    def __init__(self):
+    def __init__(self) -> None:
         """Initialize the config flow."""
         self.data_schema = vol.Schema(
             {vol.Required(CONF_USERNAME): str, vol.Required(CONF_PASSWORD): str}
         )
 
-    async def _show_form(self, errors=None):
+    async def _show_form(self, errors: dict[str, str] | None = None) -> FlowResult:
         """Show the form to the user."""
         return self.async_show_form(
             step_id="user", data_schema=self.data_schema, errors=errors or {}
         )
 
-    async def async_step_user(self, user_input=None):
+    async def async_step_user(
+        self, user_input: dict[str, str] | None = None
+    ) -> FlowResult:
         """Handle the start of the config flow."""
         if not user_input:
             return await self._show_form()
diff --git a/homeassistant/components/notion/sensor.py b/homeassistant/components/notion/sensor.py
index 650b884bf27..659b58e9815 100644
--- a/homeassistant/components/notion/sensor.py
+++ b/homeassistant/components/notion/sensor.py
@@ -14,7 +14,7 @@ SENSOR_TYPES = {SENSOR_TEMPERATURE: ("Temperature", "temperature", TEMP_CELSIUS)
 
 async def async_setup_entry(
     hass: HomeAssistant, entry: ConfigEntry, async_add_entities: AddEntitiesCallback
-):
+) -> None:
     """Set up Notion sensors based on a config entry."""
     coordinator = hass.data[DOMAIN][DATA_COORDINATOR][entry.entry_id]