diff --git a/homeassistant/components/apcupsd/sensor.py b/homeassistant/components/apcupsd/sensor.py
index a3faf6b0268..5076b537467 100644
--- a/homeassistant/components/apcupsd/sensor.py
+++ b/homeassistant/components/apcupsd/sensor.py
@@ -12,6 +12,7 @@ from homeassistant.components.sensor import (
 )
 from homeassistant.const import (
     PERCENTAGE,
+    EntityCategory,
     UnitOfApparentPower,
     UnitOfElectricCurrent,
     UnitOfElectricPotential,
@@ -35,6 +36,7 @@ SENSORS: dict[str, SensorEntityDescription] = {
     "alarmdel": SensorEntityDescription(
         key="alarmdel",
         translation_key="alarm_delay",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "ambtemp": SensorEntityDescription(
         key="ambtemp",
@@ -47,15 +49,18 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="apc",
         translation_key="apc_status",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "apcmodel": SensorEntityDescription(
         key="apcmodel",
         translation_key="apc_model",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "badbatts": SensorEntityDescription(
         key="badbatts",
         translation_key="bad_batteries",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "battdate": SensorEntityDescription(
         key="battdate",
@@ -82,6 +87,7 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="cable",
         translation_key="cable_type",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "cumonbatt": SensorEntityDescription(
         key="cumonbatt",
@@ -94,52 +100,63 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="date",
         translation_key="date",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "dipsw": SensorEntityDescription(
         key="dipsw",
         translation_key="dip_switch_settings",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "dlowbatt": SensorEntityDescription(
         key="dlowbatt",
         translation_key="low_battery_signal",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "driver": SensorEntityDescription(
         key="driver",
         translation_key="driver",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "dshutd": SensorEntityDescription(
         key="dshutd",
         translation_key="shutdown_delay",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "dwake": SensorEntityDescription(
         key="dwake",
         translation_key="wake_delay",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "end apc": SensorEntityDescription(
         key="end apc",
         translation_key="date_and_time",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "extbatts": SensorEntityDescription(
         key="extbatts",
         translation_key="external_batteries",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "firmware": SensorEntityDescription(
         key="firmware",
         translation_key="firmware_version",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "hitrans": SensorEntityDescription(
         key="hitrans",
         translation_key="transfer_high",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
         device_class=SensorDeviceClass.VOLTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "hostname": SensorEntityDescription(
         key="hostname",
         translation_key="hostname",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "humidity": SensorEntityDescription(
         key="humidity",
@@ -163,10 +180,12 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="lastxfer",
         translation_key="last_transfer",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "linefail": SensorEntityDescription(
         key="linefail",
         translation_key="line_failure",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "linefreq": SensorEntityDescription(
         key="linefreq",
@@ -198,15 +217,18 @@ SENSORS: dict[str, SensorEntityDescription] = {
         translation_key="transfer_low",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
         device_class=SensorDeviceClass.VOLTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "mandate": SensorEntityDescription(
         key="mandate",
         translation_key="manufacture_date",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "masterupd": SensorEntityDescription(
         key="masterupd",
         translation_key="master_update",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "maxlinev": SensorEntityDescription(
         key="maxlinev",
@@ -217,11 +239,13 @@ SENSORS: dict[str, SensorEntityDescription] = {
     "maxtime": SensorEntityDescription(
         key="maxtime",
         translation_key="max_time",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "mbattchg": SensorEntityDescription(
         key="mbattchg",
         translation_key="max_battery_charge",
         native_unit_of_measurement=PERCENTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "minlinev": SensorEntityDescription(
         key="minlinev",
@@ -232,41 +256,48 @@ SENSORS: dict[str, SensorEntityDescription] = {
     "mintimel": SensorEntityDescription(
         key="mintimel",
         translation_key="min_time",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "model": SensorEntityDescription(
         key="model",
         translation_key="model",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "nombattv": SensorEntityDescription(
         key="nombattv",
         translation_key="battery_nominal_voltage",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
         device_class=SensorDeviceClass.VOLTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "nominv": SensorEntityDescription(
         key="nominv",
         translation_key="nominal_input_voltage",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
         device_class=SensorDeviceClass.VOLTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "nomoutv": SensorEntityDescription(
         key="nomoutv",
         translation_key="nominal_output_voltage",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
         device_class=SensorDeviceClass.VOLTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "nompower": SensorEntityDescription(
         key="nompower",
         translation_key="nominal_output_power",
         native_unit_of_measurement=UnitOfPower.WATT,
         device_class=SensorDeviceClass.POWER,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "nomapnt": SensorEntityDescription(
         key="nomapnt",
         translation_key="nominal_apparent_power",
         native_unit_of_measurement=UnitOfApparentPower.VOLT_AMPERE,
         device_class=SensorDeviceClass.APPARENT_POWER,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "numxfers": SensorEntityDescription(
         key="numxfers",
@@ -291,21 +322,25 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="reg1",
         translation_key="register_1_fault",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "reg2": SensorEntityDescription(
         key="reg2",
         translation_key="register_2_fault",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "reg3": SensorEntityDescription(
         key="reg3",
         translation_key="register_3_fault",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "retpct": SensorEntityDescription(
         key="retpct",
         translation_key="restore_capacity",
         native_unit_of_measurement=PERCENTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "selftest": SensorEntityDescription(
         key="selftest",
@@ -315,20 +350,24 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="sense",
         translation_key="sensitivity",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "serialno": SensorEntityDescription(
         key="serialno",
         translation_key="serial_number",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "starttime": SensorEntityDescription(
         key="starttime",
         translation_key="startup_time",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "statflag": SensorEntityDescription(
         key="statflag",
         translation_key="online_status",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "status": SensorEntityDescription(
         key="status",
@@ -337,6 +376,7 @@ SENSORS: dict[str, SensorEntityDescription] = {
     "stesti": SensorEntityDescription(
         key="stesti",
         translation_key="self_test_interval",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "timeleft": SensorEntityDescription(
         key="timeleft",
@@ -360,23 +400,28 @@ SENSORS: dict[str, SensorEntityDescription] = {
         key="upsname",
         translation_key="ups_name",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "version": SensorEntityDescription(
         key="version",
         translation_key="version",
         entity_registry_enabled_default=False,
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "xoffbat": SensorEntityDescription(
         key="xoffbat",
         translation_key="transfer_from_battery",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "xoffbatt": SensorEntityDescription(
         key="xoffbatt",
         translation_key="transfer_from_battery",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
     "xonbatt": SensorEntityDescription(
         key="xonbatt",
         translation_key="transfer_to_battery",
+        entity_category=EntityCategory.DIAGNOSTIC,
     ),
 }
 
diff --git a/tests/components/apcupsd/snapshots/test_sensor.ambr b/tests/components/apcupsd/snapshots/test_sensor.ambr
index 9c0b2de4fdc..2e991d7cfa6 100644
--- a/tests/components/apcupsd/snapshots/test_sensor.ambr
+++ b/tests/components/apcupsd/snapshots/test_sensor.ambr
@@ -11,7 +11,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_alarm_delay',
     'has_entity_name': True,
     'hidden_by': None,
@@ -113,7 +113,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_battery_nominal_voltage',
     'has_entity_name': True,
     'hidden_by': None,
@@ -214,7 +214,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_battery_shutdown',
     'has_entity_name': True,
     'hidden_by': None,
@@ -263,7 +263,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_battery_timeout',
     'has_entity_name': True,
     'hidden_by': None,
@@ -368,7 +368,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_cable_type',
     'has_entity_name': True,
     'hidden_by': None,
@@ -416,7 +416,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_daemon_version',
     'has_entity_name': True,
     'hidden_by': None,
@@ -464,7 +464,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_date_and_time',
     'has_entity_name': True,
     'hidden_by': None,
@@ -512,7 +512,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_driver',
     'has_entity_name': True,
     'hidden_by': None,
@@ -560,7 +560,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_firmware_version',
     'has_entity_name': True,
     'hidden_by': None,
@@ -768,7 +768,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_last_transfer',
     'has_entity_name': True,
     'hidden_by': None,
@@ -916,7 +916,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_model',
     'has_entity_name': True,
     'hidden_by': None,
@@ -964,7 +964,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_name',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1012,7 +1012,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_nominal_apparent_power',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1065,7 +1065,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_nominal_input_voltage',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1118,7 +1118,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_nominal_output_power',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1227,7 +1227,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_self_test_interval',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1324,7 +1324,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_sensitivity',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1372,7 +1372,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_serial_number',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1420,7 +1420,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_shutdown_time',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1517,7 +1517,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_status_data',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1565,7 +1565,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_status_date',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1613,7 +1613,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_status_flag',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1880,7 +1880,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_transfer_from_battery',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1928,7 +1928,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_transfer_high',
     'has_entity_name': True,
     'hidden_by': None,
@@ -1981,7 +1981,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_transfer_low',
     'has_entity_name': True,
     'hidden_by': None,
@@ -2034,7 +2034,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.myups_transfer_to_battery',
     'has_entity_name': True,
     'hidden_by': None,