diff --git a/.strict-typing b/.strict-typing
index 0da84688727..df1e50b5f6d 100644
--- a/.strict-typing
+++ b/.strict-typing
@@ -183,6 +183,7 @@ homeassistant.components.gios.*
 homeassistant.components.glances.*
 homeassistant.components.goalzero.*
 homeassistant.components.google.*
+homeassistant.components.google_assistant_sdk.*
 homeassistant.components.google_sheets.*
 homeassistant.components.gpsd.*
 homeassistant.components.greeneye_monitor.*
diff --git a/homeassistant/components/google_assistant_sdk/helpers.py b/homeassistant/components/google_assistant_sdk/helpers.py
index 5ae39c98f3c..a55ff92afe6 100644
--- a/homeassistant/components/google_assistant_sdk/helpers.py
+++ b/homeassistant/components/google_assistant_sdk/helpers.py
@@ -104,7 +104,7 @@ async def async_send_text_commands(
         return command_response_list
 
 
-def default_language_code(hass: HomeAssistant):
+def default_language_code(hass: HomeAssistant) -> str:
     """Get default language code based on Home Assistant config."""
     language_code = f"{hass.config.language}-{hass.config.country}"
     if language_code in SUPPORTED_LANGUAGE_CODES:
diff --git a/homeassistant/components/google_assistant_sdk/notify.py b/homeassistant/components/google_assistant_sdk/notify.py
index fa117b579a9..adcd07a0cda 100644
--- a/homeassistant/components/google_assistant_sdk/notify.py
+++ b/homeassistant/components/google_assistant_sdk/notify.py
@@ -24,13 +24,13 @@ LANG_TO_BROADCAST_COMMAND = {
 }
 
 
-def broadcast_commands(language_code: str):
+def broadcast_commands(language_code: str) -> tuple[str, str]:
     """Get the commands for broadcasting a message for the given language code.
 
     Return type is a tuple where [0] is for broadcasting to your entire home,
     while [1] is for broadcasting to a specific target.
     """
-    return LANG_TO_BROADCAST_COMMAND.get(language_code.split("-", maxsplit=1)[0])
+    return LANG_TO_BROADCAST_COMMAND[language_code.split("-", maxsplit=1)[0]]
 
 
 async def async_get_service(
@@ -60,7 +60,7 @@ class BroadcastNotificationService(BaseNotificationService):
             CONF_LANGUAGE_CODE, default_language_code(self.hass)
         )
 
-        commands = []
+        commands: list[str] = []
         targets = kwargs.get(ATTR_TARGET)
         if not targets:
             commands.append(broadcast_commands(language_code)[0].format(message))
diff --git a/mypy.ini b/mypy.ini
index 9489375d9ee..26bb35d9695 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1591,6 +1591,16 @@ disallow_untyped_defs = true
 warn_return_any = true
 warn_unreachable = true
 
+[mypy-homeassistant.components.google_assistant_sdk.*]
+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.google_sheets.*]
 check_untyped_defs = true
 disallow_incomplete_defs = true