diff --git a/homeassistant/components/number/const.py b/homeassistant/components/number/const.py
index 1d82d4a5a96..83777d47322 100644
--- a/homeassistant/components/number/const.py
+++ b/homeassistant/components/number/const.py
@@ -290,7 +290,7 @@ class NumberDeviceClass(StrEnum):
     OZONE = "ozone"
     """Amount of O3.
 
-    Unit of measurement: `ppb` (parts per billion), `μg/m³`
+    Unit of measurement: `ppb` (parts per billion), `ppm` (parts per million), `μg/m³`
     """
 
     PH = "ph"
@@ -553,6 +553,7 @@ DEVICE_CLASS_UNITS: dict[NumberDeviceClass, set[type[StrEnum] | str | None]] = {
     NumberDeviceClass.NITROUS_OXIDE: {CONCENTRATION_MICROGRAMS_PER_CUBIC_METER},
     NumberDeviceClass.OZONE: {
         CONCENTRATION_PARTS_PER_BILLION,
+        CONCENTRATION_PARTS_PER_MILLION,
         CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
     },
     NumberDeviceClass.PH: {None},
diff --git a/homeassistant/components/sensor/const.py b/homeassistant/components/sensor/const.py
index 88fde1569c0..a1ee3e0417e 100644
--- a/homeassistant/components/sensor/const.py
+++ b/homeassistant/components/sensor/const.py
@@ -304,7 +304,7 @@ class SensorDeviceClass(StrEnum):
     OZONE = "ozone"
     """Amount of O3.
 
-    Unit of measurement: `ppb` (parts per billion),`μg/m³`
+    Unit of measurement: `ppb` (parts per billion), `ppm` (parts per million), `μg/m³`
     """
 
     PH = "ph"
@@ -648,6 +648,7 @@ DEVICE_CLASS_UNITS: dict[SensorDeviceClass, set[type[StrEnum] | str | None]] = {
     SensorDeviceClass.NITROUS_OXIDE: {CONCENTRATION_MICROGRAMS_PER_CUBIC_METER},
     SensorDeviceClass.OZONE: {
         CONCENTRATION_PARTS_PER_BILLION,
+        CONCENTRATION_PARTS_PER_MILLION,
         CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
     },
     SensorDeviceClass.PH: {None},
diff --git a/homeassistant/util/unit_conversion.py b/homeassistant/util/unit_conversion.py
index cad31e140fb..1f9c0c8ab90 100644
--- a/homeassistant/util/unit_conversion.py
+++ b/homeassistant/util/unit_conversion.py
@@ -526,12 +526,14 @@ class OzoneConcentrationConverter(BaseUnitConverter):
     UNIT_CLASS = "ozone"
     _UNIT_CONVERSION: dict[str | None, float] = {
         CONCENTRATION_PARTS_PER_BILLION: 1e9,
+        CONCENTRATION_PARTS_PER_MILLION: 1e6,
         CONCENTRATION_MICROGRAMS_PER_CUBIC_METER: (
             _OZONE_MOLAR_MASS / _AMBIENT_IDEAL_GAS_MOLAR_VOLUME * 1e6
         ),
     }
     VALID_UNITS = {
         CONCENTRATION_PARTS_PER_BILLION,
+        CONCENTRATION_PARTS_PER_MILLION,
         CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
     }
 
diff --git a/tests/util/test_unit_conversion.py b/tests/util/test_unit_conversion.py
index 13ba4d873cf..9deeecbd604 100644
--- a/tests/util/test_unit_conversion.py
+++ b/tests/util/test_unit_conversion.py
@@ -776,6 +776,18 @@ _CONVERTED_VALUE: dict[
             60.1378,
             CONCENTRATION_PARTS_PER_BILLION,
         ),
+        (
+            1,
+            CONCENTRATION_PARTS_PER_MILLION,
+            1995.417,
+            CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
+        ),
+        (
+            120,
+            CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
+            0.0601378,
+            CONCENTRATION_PARTS_PER_MILLION,
+        ),
     ],
     PowerConverter: [
         (10, UnitOfPower.KILO_WATT, 10000, UnitOfPower.WATT),