diff --git a/homeassistant/components/smarttub/manifest.json b/homeassistant/components/smarttub/manifest.json
index 3b8b727015b..e8db096f31d 100644
--- a/homeassistant/components/smarttub/manifest.json
+++ b/homeassistant/components/smarttub/manifest.json
@@ -7,5 +7,5 @@
   "iot_class": "cloud_polling",
   "loggers": ["smarttub"],
   "quality_scale": "platinum",
-  "requirements": ["python-smarttub==0.0.33"]
+  "requirements": ["python-smarttub==0.0.35"]
 }
diff --git a/homeassistant/components/smarttub/sensor.py b/homeassistant/components/smarttub/sensor.py
index a72555962eb..c362e1ea8f0 100644
--- a/homeassistant/components/smarttub/sensor.py
+++ b/homeassistant/components/smarttub/sensor.py
@@ -89,10 +89,14 @@ class SmartTubSensor(SmartTubSensorBase, SensorEntity):
     """Generic class for SmartTub status sensors."""
 
     @property
-    def native_value(self) -> str:
+    def native_value(self) -> str | None:
         """Return the current state of the sensor."""
+        if self._state is None:
+            return None
+
         if isinstance(self._state, Enum):
             return self._state.name.lower()
+
         return self._state.lower()
 
 
diff --git a/requirements_all.txt b/requirements_all.txt
index b4444749f4d..205ef1d5079 100644
--- a/requirements_all.txt
+++ b/requirements_all.txt
@@ -2190,7 +2190,7 @@ python-ripple-api==0.0.3
 python-roborock==0.35.0
 
 # homeassistant.components.smarttub
-python-smarttub==0.0.33
+python-smarttub==0.0.35
 
 # homeassistant.components.songpal
 python-songpal==0.15.2
diff --git a/requirements_test_all.txt b/requirements_test_all.txt
index 5360344cbf4..6fef6b5bafe 100644
--- a/requirements_test_all.txt
+++ b/requirements_test_all.txt
@@ -1634,7 +1634,7 @@ python-qbittorrent==0.4.3
 python-roborock==0.35.0
 
 # homeassistant.components.smarttub
-python-smarttub==0.0.33
+python-smarttub==0.0.35
 
 # homeassistant.components.songpal
 python-songpal==0.15.2
diff --git a/tests/components/smarttub/test_sensor.py b/tests/components/smarttub/test_sensor.py
index 5c5359df381..5e476dcaaa5 100644
--- a/tests/components/smarttub/test_sensor.py
+++ b/tests/components/smarttub/test_sensor.py
@@ -2,6 +2,7 @@
 import pytest
 import smarttub
 
+from homeassistant.const import STATE_UNKNOWN
 from homeassistant.core import HomeAssistant
 
 
@@ -27,6 +28,27 @@ async def test_sensor(
     assert state.state == expected_state
 
 
+# https://github.com/home-assistant/core/issues/102339
+async def test_null_blowoutcycle(
+    spa,
+    spa_state,
+    config_entry,
+    hass: HomeAssistant,
+) -> None:
+    """Test blowoutCycle having null value."""
+
+    spa_state.blowout_cycle = None
+
+    config_entry.add_to_hass(hass)
+    await hass.config_entries.async_setup(config_entry.entry_id)
+    await hass.async_block_till_done()
+
+    entity_id = f"sensor.{spa.brand}_{spa.model}_blowout_cycle"
+    state = hass.states.get(entity_id)
+    assert state is not None
+    assert state.state == STATE_UNKNOWN
+
+
 async def test_primary_filtration(
     spa, spa_state, setup_entry, hass: HomeAssistant
 ) -> None: