diff --git a/esphome/components/audio/__init__.py b/esphome/components/audio/__init__.py
index 9f08c81e77..06f3cf09d8 100644
--- a/esphome/components/audio/__init__.py
+++ b/esphome/components/audio/__init__.py
@@ -37,16 +37,13 @@ AUDIO_COMPONENT_SCHEMA = cv.Schema(
 )
 
 
-_UNDEF = object()
-
-
 def set_stream_limits(
-    min_bits_per_sample: int = _UNDEF,
-    max_bits_per_sample: int = _UNDEF,
-    min_channels: int = _UNDEF,
-    max_channels: int = _UNDEF,
-    min_sample_rate: int = _UNDEF,
-    max_sample_rate: int = _UNDEF,
+    min_bits_per_sample: int = cv.UNDEFINED,
+    max_bits_per_sample: int = cv.UNDEFINED,
+    min_channels: int = cv.UNDEFINED,
+    max_channels: int = cv.UNDEFINED,
+    min_sample_rate: int = cv.UNDEFINED,
+    max_sample_rate: int = cv.UNDEFINED,
 ):
     """Sets the limits for the audio stream that audio component can handle
 
@@ -55,17 +52,17 @@ def set_stream_limits(
     """
 
     def set_limits_in_config(config):
-        if min_bits_per_sample is not _UNDEF:
+        if min_bits_per_sample is not cv.UNDEFINED:
             config[CONF_MIN_BITS_PER_SAMPLE] = min_bits_per_sample
-        if max_bits_per_sample is not _UNDEF:
+        if max_bits_per_sample is not cv.UNDEFINED:
             config[CONF_MAX_BITS_PER_SAMPLE] = max_bits_per_sample
-        if min_channels is not _UNDEF:
+        if min_channels is not cv.UNDEFINED:
             config[CONF_MIN_CHANNELS] = min_channels
-        if max_channels is not _UNDEF:
+        if max_channels is not cv.UNDEFINED:
             config[CONF_MAX_CHANNELS] = max_channels
-        if min_sample_rate is not _UNDEF:
+        if min_sample_rate is not cv.UNDEFINED:
             config[CONF_MIN_SAMPLE_RATE] = min_sample_rate
-        if max_sample_rate is not _UNDEF:
+        if max_sample_rate is not cv.UNDEFINED:
             config[CONF_MAX_SAMPLE_RATE] = max_sample_rate
 
     return set_limits_in_config
@@ -75,10 +72,10 @@ def final_validate_audio_schema(
     name: str,
     *,
     audio_device: str,
-    bits_per_sample: int = _UNDEF,
-    channels: int = _UNDEF,
-    sample_rate: int = _UNDEF,
-    enabled_channels: list[int] = _UNDEF,
+    bits_per_sample: int = cv.UNDEFINED,
+    channels: int = cv.UNDEFINED,
+    sample_rate: int = cv.UNDEFINED,
+    enabled_channels: list[int] = cv.UNDEFINED,
     audio_device_issue: bool = False,
 ):
     """Validates audio compatibility when passed between different components.
@@ -101,7 +98,7 @@ def final_validate_audio_schema(
     def validate_audio_compatiblity(audio_config):
         audio_schema = {}
 
-        if bits_per_sample is not _UNDEF:
+        if bits_per_sample is not cv.UNDEFINED:
             try:
                 cv.int_range(
                     min=audio_config.get(CONF_MIN_BITS_PER_SAMPLE),
@@ -114,7 +111,7 @@ def final_validate_audio_schema(
                     error_string = f"Invalid configuration for the {name} component. The {CONF_BITS_PER_SAMPLE} {str(exc)}"
                 raise cv.Invalid(error_string) from exc
 
-        if channels is not _UNDEF:
+        if channels is not cv.UNDEFINED:
             try:
                 cv.int_range(
                     min=audio_config.get(CONF_MIN_CHANNELS),
@@ -127,7 +124,7 @@ def final_validate_audio_schema(
                     error_string = f"Invalid configuration for the {name} component. The {CONF_NUM_CHANNELS} {str(exc)}"
                 raise cv.Invalid(error_string) from exc
 
-        if sample_rate is not _UNDEF:
+        if sample_rate is not cv.UNDEFINED:
             try:
                 cv.int_range(
                     min=audio_config.get(CONF_MIN_SAMPLE_RATE),
@@ -140,7 +137,7 @@ def final_validate_audio_schema(
                     error_string = f"Invalid configuration for the {name} component. The {CONF_SAMPLE_RATE} {str(exc)}"
                 raise cv.Invalid(error_string) from exc
 
-        if enabled_channels is not _UNDEF:
+        if enabled_channels is not cv.UNDEFINED:
             for channel in enabled_channels:
                 try:
                     # Channels are 0-indexed
diff --git a/esphome/components/binary_sensor/__init__.py b/esphome/components/binary_sensor/__init__.py
index d947c2aba6..d0fed9a9b8 100644
--- a/esphome/components/binary_sensor/__init__.py
+++ b/esphome/components/binary_sensor/__init__.py
@@ -458,19 +458,17 @@ BINARY_SENSOR_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def binary_sensor_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    icon: str = _UNDEF,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = {}
 
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         # Not cv.optional
         schema[cv.GenerateID()] = cv.declare_id(class_)
 
@@ -479,7 +477,7 @@ def binary_sensor_schema(
         (CONF_ENTITY_CATEGORY, entity_category, cv.entity_category),
         (CONF_DEVICE_CLASS, device_class, validate_device_class),
     ]:
-        if default is not _UNDEF:
+        if default is not cv.UNDEFINED:
             schema[cv.Optional(key, default=default)] = validator
 
     return BINARY_SENSOR_SCHEMA.extend(schema)
diff --git a/esphome/components/button/__init__.py b/esphome/components/button/__init__.py
index 366d0edf7d..0307fd3f03 100644
--- a/esphome/components/button/__init__.py
+++ b/esphome/components/button/__init__.py
@@ -60,15 +60,13 @@ BUTTON_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def button_schema(
     class_: MockObjClass,
     *,
-    icon: str = _UNDEF,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = {cv.GenerateID(): cv.declare_id(class_)}
 
@@ -77,7 +75,7 @@ def button_schema(
         (CONF_ENTITY_CATEGORY, entity_category, cv.entity_category),
         (CONF_DEVICE_CLASS, device_class, validate_device_class),
     ]:
-        if default is not _UNDEF:
+        if default is not cv.UNDEFINED:
             schema[cv.Optional(key, default=default)] = validator
 
     return BUTTON_SCHEMA.extend(schema)
diff --git a/esphome/components/event/__init__.py b/esphome/components/event/__init__.py
index a7732dfcaf..99a698e8eb 100644
--- a/esphome/components/event/__init__.py
+++ b/esphome/components/event/__init__.py
@@ -58,19 +58,17 @@ EVENT_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def event_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    icon: str = _UNDEF,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = {}
 
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         schema[cv.GenerateID()] = cv.declare_id(class_)
 
     for key, default, validator in [
@@ -78,7 +76,7 @@ def event_schema(
         (CONF_ENTITY_CATEGORY, entity_category, cv.entity_category),
         (CONF_DEVICE_CLASS, device_class, validate_device_class),
     ]:
-        if default is not _UNDEF:
+        if default is not cv.UNDEFINED:
             schema[cv.Optional(key, default=default)] = validator
 
     return EVENT_SCHEMA.extend(schema)
diff --git a/esphome/components/microphone/__init__.py b/esphome/components/microphone/__init__.py
index f85f0b76f3..2fda99af05 100644
--- a/esphome/components/microphone/__init__.py
+++ b/esphome/components/microphone/__init__.py
@@ -123,11 +123,8 @@ def microphone_source_schema(
     )
 
 
-_UNDEF = object()
-
-
 def final_validate_microphone_source_schema(
-    component_name: str, sample_rate: int = _UNDEF
+    component_name: str, sample_rate: int = cv.UNDEFINED
 ):
     """Validates that the microphone source can provide audio in the correct format. In particular it validates the sample rate and the enabled channels.
 
@@ -141,7 +138,7 @@ def final_validate_microphone_source_schema(
     """
 
     def _validate_audio_compatability(config):
-        if sample_rate is not _UNDEF:
+        if sample_rate is not cv.UNDEFINED:
             # Issues require changing the microphone configuration
             #  - Verifies sample rates match
             audio.final_validate_audio_schema(
diff --git a/esphome/components/number/__init__.py b/esphome/components/number/__init__.py
index f45cfd54f2..0f68065805 100644
--- a/esphome/components/number/__init__.py
+++ b/esphome/components/number/__init__.py
@@ -196,16 +196,14 @@ NUMBER_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def number_schema(
     class_: MockObjClass,
     *,
-    icon: str = _UNDEF,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
-    unit_of_measurement: str = _UNDEF,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
+    unit_of_measurement: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = {cv.GenerateID(): cv.declare_id(class_)}
 
@@ -215,7 +213,7 @@ def number_schema(
         (CONF_DEVICE_CLASS, device_class, validate_device_class),
         (CONF_UNIT_OF_MEASUREMENT, unit_of_measurement, validate_unit_of_measurement),
     ]:
-        if default is not _UNDEF:
+        if default is not cv.UNDEFINED:
             schema[cv.Optional(key, default=default)] = validator
 
     return NUMBER_SCHEMA.extend(schema)
diff --git a/esphome/components/opentherm/binary_sensor/__init__.py b/esphome/components/opentherm/binary_sensor/__init__.py
index d4c7861a1d..ce5a701a53 100644
--- a/esphome/components/opentherm/binary_sensor/__init__.py
+++ b/esphome/components/opentherm/binary_sensor/__init__.py
@@ -12,9 +12,9 @@ COMPONENT_TYPE = const.BINARY_SENSOR
 def get_entity_validation_schema(entity: schema.BinarySensorSchema) -> cv.Schema:
     return binary_sensor.binary_sensor_schema(
         device_class=(
-            entity.device_class or binary_sensor._UNDEF  # pylint: disable=protected-access
+            entity.device_class or cv.UNDEFINED  # pylint: disable=protected-access
         ),
-        icon=(entity.icon or binary_sensor._UNDEF),  # pylint: disable=protected-access
+        icon=(entity.icon or cv.UNDEFINED),  # pylint: disable=protected-access
     )
 
 
diff --git a/esphome/components/opentherm/sensor/__init__.py b/esphome/components/opentherm/sensor/__init__.py
index 86c842b299..9aa33f457d 100644
--- a/esphome/components/opentherm/sensor/__init__.py
+++ b/esphome/components/opentherm/sensor/__init__.py
@@ -23,10 +23,10 @@ MSG_DATA_TYPES = {
 
 def get_entity_validation_schema(entity: schema.SensorSchema) -> cv.Schema:
     return sensor.sensor_schema(
-        unit_of_measurement=entity.unit_of_measurement or sensor._UNDEF,  # pylint: disable=protected-access
+        unit_of_measurement=entity.unit_of_measurement or cv.UNDEFINED,  # pylint: disable=protected-access
         accuracy_decimals=entity.accuracy_decimals,
-        device_class=entity.device_class or sensor._UNDEF,  # pylint: disable=protected-access
-        icon=entity.icon or sensor._UNDEF,  # pylint: disable=protected-access
+        device_class=entity.device_class or cv.UNDEFINED,  # pylint: disable=protected-access
+        icon=entity.icon or cv.UNDEFINED,  # pylint: disable=protected-access
         state_class=entity.state_class,
     ).extend(
         {
diff --git a/esphome/components/select/__init__.py b/esphome/components/select/__init__.py
index 5a3271fdfd..106571d94d 100644
--- a/esphome/components/select/__init__.py
+++ b/esphome/components/select/__init__.py
@@ -64,19 +64,17 @@ SELECT_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def select_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    entity_category: str = _UNDEF,
-    icon: str = _UNDEF,
+    entity_category: str = cv.UNDEFINED,
+    icon: str = cv.UNDEFINED,
 ):
     schema = cv.Schema({})
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         schema = schema.extend({cv.GenerateID(): cv.declare_id(class_)})
-    if entity_category is not _UNDEF:
+    if entity_category is not cv.UNDEFINED:
         schema = schema.extend(
             {
                 cv.Optional(
@@ -84,7 +82,7 @@ def select_schema(
                 ): cv.entity_category
             }
         )
-    if icon is not _UNDEF:
+    if icon is not cv.UNDEFINED:
         schema = schema.extend({cv.Optional(CONF_ICON, default=icon): cv.icon})
     return SELECT_SCHEMA.extend(schema)
 
diff --git a/esphome/components/sensor/__init__.py b/esphome/components/sensor/__init__.py
index 5f990466c8..1eb2d67d6e 100644
--- a/esphome/components/sensor/__init__.py
+++ b/esphome/components/sensor/__init__.py
@@ -309,22 +309,20 @@ SENSOR_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def sensor_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    unit_of_measurement: str = _UNDEF,
-    icon: str = _UNDEF,
-    accuracy_decimals: int = _UNDEF,
-    device_class: str = _UNDEF,
-    state_class: str = _UNDEF,
-    entity_category: str = _UNDEF,
+    unit_of_measurement: str = cv.UNDEFINED,
+    icon: str = cv.UNDEFINED,
+    accuracy_decimals: int = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
+    state_class: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = {}
 
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         # Not optional.
         schema[cv.GenerateID()] = cv.declare_id(class_)
 
@@ -336,7 +334,7 @@ def sensor_schema(
         (CONF_STATE_CLASS, state_class, validate_state_class),
         (CONF_ENTITY_CATEGORY, entity_category, sensor_entity_category),
     ]:
-        if default is not _UNDEF:
+        if default is not cv.UNDEFINED:
             schema[cv.Optional(key, default=default)] = validator
 
     return SENSOR_SCHEMA.extend(schema)
@@ -811,7 +809,9 @@ async def setup_sensor_core_(var, config):
         mqtt_ = cg.new_Pvariable(mqtt_id, var)
         await mqtt.register_mqtt_component(mqtt_, config)
 
-        if (expire_after := config.get(CONF_EXPIRE_AFTER, _UNDEF)) is not _UNDEF:
+        if (
+            expire_after := config.get(CONF_EXPIRE_AFTER, cv.UNDEFINED)
+        ) is not cv.UNDEFINED:
             if expire_after is None:
                 cg.add(mqtt_.disable_expire_after())
             else:
diff --git a/esphome/components/switch/__init__.py b/esphome/components/switch/__init__.py
index 0f159f69ec..fa69cf1440 100644
--- a/esphome/components/switch/__init__.py
+++ b/esphome/components/switch/__init__.py
@@ -87,15 +87,13 @@ _SWITCH_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def switch_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
-    icon: str = _UNDEF,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
+    icon: str = cv.UNDEFINED,
     block_inverted: bool = False,
     default_restore_mode: str = "ALWAYS_OFF",
 ):
@@ -106,9 +104,9 @@ def switch_schema(
             ),
         }
     )
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         schema = schema.extend({cv.GenerateID(): cv.declare_id(class_)})
-    if entity_category is not _UNDEF:
+    if entity_category is not cv.UNDEFINED:
         schema = schema.extend(
             {
                 cv.Optional(
@@ -116,7 +114,7 @@ def switch_schema(
                 ): cv.entity_category
             }
         )
-    if device_class is not _UNDEF:
+    if device_class is not cv.UNDEFINED:
         schema = schema.extend(
             {
                 cv.Optional(
@@ -124,7 +122,7 @@ def switch_schema(
                 ): validate_device_class
             }
         )
-    if icon is not _UNDEF:
+    if icon is not cv.UNDEFINED:
         schema = schema.extend({cv.Optional(CONF_ICON, default=icon): cv.icon})
     if block_inverted:
         schema = schema.extend(
diff --git a/esphome/components/text_sensor/__init__.py b/esphome/components/text_sensor/__init__.py
index 12993d9ffc..046af2bd26 100644
--- a/esphome/components/text_sensor/__init__.py
+++ b/esphome/components/text_sensor/__init__.py
@@ -152,22 +152,20 @@ TEXT_SENSOR_SCHEMA = (
     )
 )
 
-_UNDEF = object()
-
 
 def text_sensor_schema(
-    class_: MockObjClass = _UNDEF,
+    class_: MockObjClass = cv.UNDEFINED,
     *,
-    icon: str = _UNDEF,
-    entity_category: str = _UNDEF,
-    device_class: str = _UNDEF,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+    device_class: str = cv.UNDEFINED,
 ) -> cv.Schema:
     schema = TEXT_SENSOR_SCHEMA
-    if class_ is not _UNDEF:
+    if class_ is not cv.UNDEFINED:
         schema = schema.extend({cv.GenerateID(): cv.declare_id(class_)})
-    if icon is not _UNDEF:
+    if icon is not cv.UNDEFINED:
         schema = schema.extend({cv.Optional(CONF_ICON, default=icon): cv.icon})
-    if device_class is not _UNDEF:
+    if device_class is not cv.UNDEFINED:
         schema = schema.extend(
             {
                 cv.Optional(
@@ -175,7 +173,7 @@ def text_sensor_schema(
                 ): validate_device_class
             }
         )
-    if entity_category is not _UNDEF:
+    if entity_category is not cv.UNDEFINED:
         schema = schema.extend(
             {
                 cv.Optional(