diff --git a/homeassistant/components/systemmonitor/coordinator.py b/homeassistant/components/systemmonitor/coordinator.py
index d12eddbb14a..32a171a11ca 100644
--- a/homeassistant/components/systemmonitor/coordinator.py
+++ b/homeassistant/components/systemmonitor/coordinator.py
@@ -37,17 +37,29 @@ class SensorData:
 
     def as_dict(self) -> dict[str, Any]:
         """Return as dict."""
+        disk_usage = None
+        if self.disk_usage:
+            disk_usage = {k: str(v) for k, v in self.disk_usage.items()}
+        io_counters = None
+        if self.io_counters:
+            io_counters = {k: str(v) for k, v in self.io_counters.items()}
+        addresses = None
+        if self.addresses:
+            addresses = {k: str(v) for k, v in self.addresses.items()}
+        temperatures = None
+        if self.temperatures:
+            temperatures = {k: str(v) for k, v in self.temperatures.items()}
         return {
-            "disk_usage": {k: str(v) for k, v in self.disk_usage.items()},
+            "disk_usage": disk_usage,
             "swap": str(self.swap),
             "memory": str(self.memory),
-            "io_counters": {k: str(v) for k, v in self.io_counters.items()},
-            "addresses": {k: str(v) for k, v in self.addresses.items()},
+            "io_counters": io_counters,
+            "addresses": addresses,
             "load": str(self.load),
             "cpu_percent": str(self.cpu_percent),
             "boot_time": str(self.boot_time),
             "processes": str(self.processes),
-            "temperatures": {k: str(v) for k, v in self.temperatures.items()},
+            "temperatures": temperatures,
         }
 
 
diff --git a/tests/components/systemmonitor/snapshots/test_diagnostics.ambr b/tests/components/systemmonitor/snapshots/test_diagnostics.ambr
index 303074e3c2c..75d942fc601 100644
--- a/tests/components/systemmonitor/snapshots/test_diagnostics.ambr
+++ b/tests/components/systemmonitor/snapshots/test_diagnostics.ambr
@@ -62,3 +62,58 @@
     }),
   })
 # ---
+# name: test_diagnostics_missing_items[test_diagnostics_missing_items]
+  dict({
+    'coordinators': dict({
+      'data': dict({
+        'addresses': None,
+        'boot_time': '2024-02-24 15:00:00+00:00',
+        'cpu_percent': '10.0',
+        'disk_usage': dict({
+          '/': 'sdiskusage(total=536870912000, used=322122547200, free=214748364800, percent=60.0)',
+          '/home/notexist/': 'sdiskusage(total=536870912000, used=322122547200, free=214748364800, percent=60.0)',
+          '/media/share': 'sdiskusage(total=536870912000, used=322122547200, free=214748364800, percent=60.0)',
+        }),
+        'io_counters': None,
+        'load': '(1, 2, 3)',
+        'memory': 'VirtualMemory(total=104857600, available=41943040, percent=40.0, used=62914560, free=31457280)',
+        'processes': "[tests.components.systemmonitor.conftest.MockProcess(pid=1, name='python3', status='sleeping', started='2024-02-23 15:00:00'), tests.components.systemmonitor.conftest.MockProcess(pid=1, name='pip', status='sleeping', started='2024-02-23 15:00:00')]",
+        'swap': 'sswap(total=104857600, used=62914560, free=41943040, percent=60.0, sin=1, sout=1)',
+        'temperatures': dict({
+          'cpu0-thermal': "[shwtemp(label='cpu0-thermal', current=50.0, high=60.0, critical=70.0)]",
+        }),
+      }),
+      'last_update_success': True,
+    }),
+    'entry': dict({
+      'data': dict({
+      }),
+      'disabled_by': None,
+      'discovery_keys': dict({
+      }),
+      'domain': 'systemmonitor',
+      'minor_version': 3,
+      'options': dict({
+        'binary_sensor': dict({
+          'process': list([
+            'python3',
+            'pip',
+          ]),
+        }),
+        'resources': list([
+          'disk_use_percent_/',
+          'disk_use_percent_/home/notexist/',
+          'memory_free_',
+          'network_out_eth0',
+          'process_python3',
+        ]),
+      }),
+      'pref_disable_new_entities': False,
+      'pref_disable_polling': False,
+      'source': 'user',
+      'title': 'System Monitor',
+      'unique_id': None,
+      'version': 1,
+    }),
+  })
+# ---
diff --git a/tests/components/systemmonitor/test_diagnostics.py b/tests/components/systemmonitor/test_diagnostics.py
index b0f4fca3d0c..26e421e6574 100644
--- a/tests/components/systemmonitor/test_diagnostics.py
+++ b/tests/components/systemmonitor/test_diagnostics.py
@@ -2,6 +2,7 @@
 
 from unittest.mock import Mock
 
+from freezegun.api import FrozenDateTimeFactory
 from syrupy import SnapshotAssertion
 from syrupy.filters import props
 
@@ -24,3 +25,26 @@ async def test_diagnostics(
     assert await get_diagnostics_for_config_entry(
         hass, hass_client, mock_added_config_entry
     ) == snapshot(exclude=props("last_update", "entry_id", "created_at", "modified_at"))
+
+
+async def test_diagnostics_missing_items(
+    hass: HomeAssistant,
+    hass_client: ClientSessionGenerator,
+    mock_psutil: Mock,
+    mock_os: Mock,
+    mock_config_entry: MockConfigEntry,
+    snapshot: SnapshotAssertion,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test diagnostics."""
+    mock_psutil.net_if_addrs.return_value = None
+    mock_psutil.net_io_counters.return_value = None
+    mock_config_entry.add_to_hass(hass)
+    await hass.config_entries.async_setup(mock_config_entry.entry_id)
+
+    assert await get_diagnostics_for_config_entry(
+        hass, hass_client, mock_config_entry
+    ) == snapshot(
+        exclude=props("last_update", "entry_id", "created_at", "modified_at"),
+        name="test_diagnostics_missing_items",
+    )