diff --git a/homeassistant/components/homematic/binary_sensor.py b/homeassistant/components/homematic/binary_sensor.py
index 4d8b4178f54..e2090b74ce8 100644
--- a/homeassistant/components/homematic/binary_sensor.py
+++ b/homeassistant/components/homematic/binary_sensor.py
@@ -59,7 +59,7 @@ class HMBinarySensor(HMDevice, BinarySensorEntity):
     """Representation of a binary HomeMatic device."""
 
     @property
-    def is_on(self):
+    def is_on(self) -> bool:
         """Return true if switch is on."""
         if not self.available:
             return False
@@ -73,7 +73,7 @@ class HMBinarySensor(HMDevice, BinarySensorEntity):
             return BinarySensorDeviceClass.MOTION
         return SENSOR_TYPES_CLASS.get(self._hmdevice.__class__.__name__)
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate the data dictionary (self._data) from metadata."""
         # Add state to data struct
         if self._state:
@@ -86,11 +86,11 @@ class HMBatterySensor(HMDevice, BinarySensorEntity):
     _attr_device_class = BinarySensorDeviceClass.BATTERY
 
     @property
-    def is_on(self):
+    def is_on(self) -> bool:
         """Return True if battery is low."""
         return bool(self._hm_get_state())
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate the data dictionary (self._data) from metadata."""
         # Add state to data struct
         if self._state:
diff --git a/homeassistant/components/homematic/climate.py b/homeassistant/components/homematic/climate.py
index 28943774b6c..096ad76db11 100644
--- a/homeassistant/components/homematic/climate.py
+++ b/homeassistant/components/homematic/climate.py
@@ -178,7 +178,7 @@ class HMThermostat(HMDevice, ClimateEntity):
         # Homematic
         return self._data.get("CONTROL_MODE")
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dict (self._data) from the Homematic metadata."""
         self._state = next(iter(self._hmdevice.WRITENODE.keys()))
         self._data[self._state] = None
diff --git a/homeassistant/components/homematic/cover.py b/homeassistant/components/homematic/cover.py
index b9f4a4fa96a..f93d92eed56 100644
--- a/homeassistant/components/homematic/cover.py
+++ b/homeassistant/components/homematic/cover.py
@@ -78,7 +78,7 @@ class HMCover(HMDevice, CoverEntity):
         """Stop the device if in motion."""
         self._hmdevice.stop(self._channel)
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dictionary (self._data) from metadata."""
         self._state = "LEVEL"
         self._data.update({self._state: None})
@@ -138,7 +138,7 @@ class HMGarage(HMCover):
         """Return whether the cover is closed."""
         return self._hmdevice.is_closed(self._hm_get_state())
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dictionary (self._data) from metadata."""
         self._state = "DOOR_STATE"
         self._data.update({self._state: None})
diff --git a/homeassistant/components/homematic/entity.py b/homeassistant/components/homematic/entity.py
index 3b5d2ebb509..3e4d6a6fc71 100644
--- a/homeassistant/components/homematic/entity.py
+++ b/homeassistant/components/homematic/entity.py
@@ -204,7 +204,7 @@ class HMDevice(Entity):
         self._init_data_struct()
 
     @abstractmethod
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dictionary from the HomeMatic device metadata."""
 
 
diff --git a/homeassistant/components/homematic/light.py b/homeassistant/components/homematic/light.py
index 838cdc9c3c3..62ce1cc9457 100644
--- a/homeassistant/components/homematic/light.py
+++ b/homeassistant/components/homematic/light.py
@@ -51,7 +51,7 @@ class HMLight(HMDevice, LightEntity):
     _attr_max_color_temp_kelvin = 6500  # 153 Mireds
 
     @property
-    def brightness(self):
+    def brightness(self) -> int | None:
         """Return the brightness of this light between 0..255."""
         # Is dimmer?
         if self._state == "LEVEL":
@@ -59,7 +59,7 @@ class HMLight(HMDevice, LightEntity):
         return None
 
     @property
-    def is_on(self):
+    def is_on(self) -> bool:
         """Return true if light is on."""
         try:
             return self._hm_get_state() > 0
@@ -98,7 +98,7 @@ class HMLight(HMDevice, LightEntity):
         return features
 
     @property
-    def hs_color(self):
+    def hs_color(self) -> tuple[float, float] | None:
         """Return the hue and saturation color value [float, float]."""
         if ColorMode.HS not in self.supported_color_modes:
             return None
@@ -116,14 +116,14 @@ class HMLight(HMDevice, LightEntity):
         )
 
     @property
-    def effect_list(self):
+    def effect_list(self) -> list[str] | None:
         """Return the list of supported effects."""
         if not self.supported_features & LightEntityFeature.EFFECT:
             return None
         return self._hmdevice.get_effect_list()
 
     @property
-    def effect(self):
+    def effect(self) -> str | None:
         """Return the current color change program of the light."""
         if not self.supported_features & LightEntityFeature.EFFECT:
             return None
@@ -166,7 +166,7 @@ class HMLight(HMDevice, LightEntity):
 
         self._hmdevice.off(self._channel)
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dict (self._data) from the Homematic metadata."""
         # Use LEVEL
         self._state = "LEVEL"
diff --git a/homeassistant/components/homematic/lock.py b/homeassistant/components/homematic/lock.py
index b79f28f2bc7..7640146b422 100644
--- a/homeassistant/components/homematic/lock.py
+++ b/homeassistant/components/homematic/lock.py
@@ -48,7 +48,7 @@ class HMLock(HMDevice, LockEntity):
         """Open the door latch."""
         self._hmdevice.open()
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate the data dictionary (self._data) from metadata."""
         self._state = "STATE"
         self._data.update({self._state: None})
diff --git a/homeassistant/components/homematic/sensor.py b/homeassistant/components/homematic/sensor.py
index bdd446d7091..0ddc319626e 100644
--- a/homeassistant/components/homematic/sensor.py
+++ b/homeassistant/components/homematic/sensor.py
@@ -339,7 +339,7 @@ class HMSensor(HMDevice, SensorEntity):
         # No cast, return original value
         return self._hm_get_state()
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate a data dictionary (self._data) from metadata."""
         if self._state:
             self._data.update({self._state: None})
diff --git a/homeassistant/components/homematic/switch.py b/homeassistant/components/homematic/switch.py
index 5f7c1f93dc8..ac8a2e5fe14 100644
--- a/homeassistant/components/homematic/switch.py
+++ b/homeassistant/components/homematic/switch.py
@@ -35,7 +35,7 @@ class HMSwitch(HMDevice, SwitchEntity):
     """Representation of a HomeMatic switch."""
 
     @property
-    def is_on(self):
+    def is_on(self) -> bool:
         """Return True if switch is on."""
         try:
             return self._hm_get_state() > 0
@@ -43,7 +43,7 @@ class HMSwitch(HMDevice, SwitchEntity):
             return False
 
     @property
-    def today_energy_kwh(self):
+    def today_energy_kwh(self) -> float | None:
         """Return the current power usage in kWh."""
         if "ENERGY_COUNTER" in self._data:
             try:
@@ -61,7 +61,7 @@ class HMSwitch(HMDevice, SwitchEntity):
         """Turn the switch off."""
         self._hmdevice.off(self._channel)
 
-    def _init_data_struct(self):
+    def _init_data_struct(self) -> None:
         """Generate the data dictionary (self._data) from metadata."""
         self._state = "STATE"
         self._data.update({self._state: None})