diff --git a/homeassistant/components/teslemetry/__init__.py b/homeassistant/components/teslemetry/__init__.py
index 3ffd16c5ba5..765f345898c 100644
--- a/homeassistant/components/teslemetry/__init__.py
+++ b/homeassistant/components/teslemetry/__init__.py
@@ -102,7 +102,11 @@ async def _get_access_token(oauth_session: OAuth2Session) -> str:
 async def async_setup_entry(hass: HomeAssistant, entry: TeslemetryConfigEntry) -> bool:
     """Set up Teslemetry config."""
 
-    session = async_get_clientsession(hass)
+    if "token" not in entry.data:
+        raise ConfigEntryAuthFailed(
+            translation_domain=DOMAIN,
+            translation_key="token_data_malformed",
+        )
 
     try:
         implementation = await async_get_config_entry_implementation(hass, entry)
@@ -113,6 +117,8 @@ async def async_setup_entry(hass: HomeAssistant, entry: TeslemetryConfigEntry) -
         ) from err
     oauth_session = OAuth2Session(hass, entry, implementation)
 
+    session = async_get_clientsession(hass)
+
     # Create API connection
     access_token = partial(_get_access_token, oauth_session)
     teslemetry = Teslemetry(
diff --git a/tests/components/teslemetry/test_init.py b/tests/components/teslemetry/test_init.py
index 18e8dc48039..c84653d16a3 100644
--- a/tests/components/teslemetry/test_init.py
+++ b/tests/components/teslemetry/test_init.py
@@ -649,6 +649,26 @@ async def test_live_status_generic_error(
         assert entry.state is ConfigEntryState.LOADED
 
 
+async def test_missing_token_data(hass: HomeAssistant) -> None:
+    """Test that missing token data in config entry triggers auth failure."""
+    mock_entry = MockConfigEntry(
+        domain=DOMAIN,
+        version=2,
+        unique_id=UNIQUE_ID,
+        data={
+            "auth_implementation": DOMAIN,
+            # token is intentionally missing
+        },
+    )
+    mock_entry.add_to_hass(hass)
+    await hass.config_entries.async_setup(mock_entry.entry_id)
+    await hass.async_block_till_done()
+
+    entry = hass.config_entries.async_get_entry(mock_entry.entry_id)
+    assert entry is not None
+    assert entry.state is ConfigEntryState.SETUP_ERROR
+
+
 async def test_vehicle_streaming_version_update(
     hass: HomeAssistant,
     device_registry: dr.DeviceRegistry,