diff --git a/homeassistant/components/google/__init__.py b/homeassistant/components/google/__init__.py
index f158db884dc..3df1cf194f0 100644
--- a/homeassistant/components/google/__init__.py
+++ b/homeassistant/components/google/__init__.py
@@ -185,8 +185,14 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
             hass, entry
         )
     )
-    assert isinstance(implementation, DeviceAuth)
     session = config_entry_oauth2_flow.OAuth2Session(hass, entry, implementation)
+    # Force a token refresh to fix a bug where tokens were persisted with
+    # expires_in (relative time delta) and expires_at (absolute time) swapped.
+    if session.token["expires_at"] >= datetime(2070, 1, 1).timestamp():
+        session.token["expires_in"] = 0
+        session.token["expires_at"] = datetime.now().timestamp()
+        await session.async_ensure_token_valid()
+
     required_scope = hass.data[DOMAIN][DATA_CONFIG][CONF_CALENDAR_ACCESS].scope
     if required_scope not in session.token.get("scope", []):
         raise ConfigEntryAuthFailed(
diff --git a/tests/components/google/conftest.py b/tests/components/google/conftest.py
index 102b8a1ccc6..617590cb856 100644
--- a/tests/components/google/conftest.py
+++ b/tests/components/google/conftest.py
@@ -132,9 +132,16 @@ async def token_scopes() -> list[str]:
 
 
 @pytest.fixture
-async def creds(token_scopes: list[str]) -> OAuth2Credentials:
+def token_expiry() -> datetime.datetime:
+    """Expiration time for credentials used in the test."""
+    return utcnow() + datetime.timedelta(days=7)
+
+
+@pytest.fixture
+def creds(
+    token_scopes: list[str], token_expiry: datetime.datetime
+) -> OAuth2Credentials:
     """Fixture that defines creds used in the test."""
-    token_expiry = utcnow() + datetime.timedelta(days=7)
     return OAuth2Credentials(
         access_token="ACCESS_TOKEN",
         client_id="client-id",
@@ -156,9 +163,16 @@ async def storage() -> YieldFixture[FakeStorage]:
 
 
 @pytest.fixture
-async def config_entry(token_scopes: list[str]) -> MockConfigEntry:
+def config_entry_token_expiry(token_expiry: datetime.datetime) -> float:
+    """Fixture for token expiration value stored in the config entry."""
+    return token_expiry.timestamp()
+
+
+@pytest.fixture
+async def config_entry(
+    token_scopes: list[str], config_entry_token_expiry: float
+) -> MockConfigEntry:
     """Fixture to create a config entry for the integration."""
-    token_expiry = utcnow() + datetime.timedelta(days=7)
     return MockConfigEntry(
         domain=DOMAIN,
         data={
@@ -168,7 +182,7 @@ async def config_entry(token_scopes: list[str]) -> MockConfigEntry:
                 "refresh_token": "REFRESH_TOKEN",
                 "scope": " ".join(token_scopes),
                 "token_type": "Bearer",
-                "expires_at": token_expiry.timestamp(),
+                "expires_at": config_entry_token_expiry,
             },
         },
     )
diff --git a/tests/components/google/test_init.py b/tests/components/google/test_init.py
index 82d7f53fe4f..124db5c0960 100644
--- a/tests/components/google/test_init.py
+++ b/tests/components/google/test_init.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 
 from collections.abc import Awaitable, Callable
 import datetime
+import time
 from typing import Any
 from unittest.mock import Mock, call, patch
 
@@ -29,6 +30,7 @@ from .conftest import (
 )
 
 from tests.common import MockConfigEntry
+from tests.test_util.aiohttp import AiohttpClientMocker
 
 # Typing helpers
 HassApi = Callable[[], Awaitable[dict[str, Any]]]
@@ -471,3 +473,37 @@ async def test_scan_calendars(
     assert state
     assert state.name == "Calendar 2"
     assert state.state == STATE_OFF
+
+
+@pytest.mark.parametrize(
+    "config_entry_token_expiry", [datetime.datetime.max.timestamp() + 1]
+)
+async def test_invalid_token_expiry_in_config_entry(
+    hass: HomeAssistant,
+    component_setup: ComponentSetup,
+    setup_config_entry: MockConfigEntry,
+    aioclient_mock: AiohttpClientMocker,
+) -> None:
+    """Exercise case in issue #69623 with invalid token expiration persisted."""
+
+    # The token is refreshed and new expiration values are returned
+    expires_in = 86400
+    expires_at = time.time() + expires_in
+    aioclient_mock.post(
+        "https://oauth2.googleapis.com/token",
+        json={
+            "refresh_token": "some-refresh-token",
+            "access_token": "some-updated-token",
+            "expires_at": expires_at,
+            "expires_in": expires_in,
+        },
+    )
+
+    assert await component_setup()
+
+    # Verify token expiration values are updated
+    entries = hass.config_entries.async_entries(DOMAIN)
+    assert len(entries) == 1
+    assert entries[0].state is ConfigEntryState.LOADED
+    assert entries[0].data["token"]["access_token"] == "some-updated-token"
+    assert entries[0].data["token"]["expires_in"] == expires_in