diff --git a/homeassistant/components/camera/prefs.py b/homeassistant/components/camera/prefs.py
index 28e4e1eeacb..160f896c86c 100644
--- a/homeassistant/components/camera/prefs.py
+++ b/homeassistant/components/camera/prefs.py
@@ -1,6 +1,7 @@
 """Preference management for camera component."""
 from __future__ import annotations
 
+from collections.abc import Mapping
 from dataclasses import asdict, dataclass
 from typing import Final, cast
 
@@ -89,7 +90,7 @@ class CameraPreferences:
         # Get preload stream setting from prefs
         # Get orientation setting from entity registry
         reg_entry = er.async_get(self._hass).async_get(entity_id)
-        er_prefs = reg_entry.options.get(DOMAIN, {}) if reg_entry else {}
+        er_prefs: Mapping = reg_entry.options.get(DOMAIN, {}) if reg_entry else {}
         preload_prefs = await self._store.async_load() or {}
         settings = DynamicStreamSettings(
             preload_stream=cast(
diff --git a/homeassistant/components/sensor/__init__.py b/homeassistant/components/sensor/__init__.py
index 1812f41693d..4f56be77a94 100644
--- a/homeassistant/components/sensor/__init__.py
+++ b/homeassistant/components/sensor/__init__.py
@@ -737,7 +737,7 @@ class SensorEntity(Entity):
             or "suggested_display_precision" not in self.registry_entry.options
         ):
             return
-        sensor_options = self.registry_entry.options.get(DOMAIN, {})
+        sensor_options: Mapping[str, Any] = self.registry_entry.options.get(DOMAIN, {})
         if (
             "suggested_display_precision" in sensor_options
             and sensor_options["suggested_display_precision"] == display_precision
diff --git a/homeassistant/helpers/entity_registry.py b/homeassistant/helpers/entity_registry.py
index 4c192d916c1..9cb119b81b4 100644
--- a/homeassistant/helpers/entity_registry.py
+++ b/homeassistant/helpers/entity_registry.py
@@ -12,6 +12,7 @@ from __future__ import annotations
 from collections import UserDict
 from collections.abc import Callable, Iterable, Mapping, ValuesView
 import logging
+from types import MappingProxyType
 from typing import TYPE_CHECKING, Any, TypeVar, cast
 
 import attr
@@ -111,6 +112,29 @@ DISLAY_DICT_OPTIONAL = (
 )
 
 
+class _EntityOptions(UserDict[str, MappingProxyType]):
+    """Container for entity options."""
+
+    def __init__(self, data: Mapping[str, Mapping] | None) -> None:
+        """Initialize."""
+        super().__init__()
+        if data is None:
+            return
+        self.data = {key: MappingProxyType(val) for key, val in data.items()}
+
+    def __setitem__(self, key: str, entry: Mapping) -> None:
+        """Add an item."""
+        raise NotImplementedError
+
+    def __delitem__(self, key: str) -> None:
+        """Remove an item."""
+        raise NotImplementedError
+
+    def as_dict(self) -> dict[str, dict]:
+        """Return dictionary version."""
+        return {key: dict(val) for key, val in self.data.items()}
+
+
 @attr.s(slots=True, frozen=True)
 class RegistryEntry:
     """Entity Registry Entry."""
@@ -132,10 +156,7 @@ class RegistryEntry:
     id: str = attr.ib(factory=uuid_util.random_uuid_hex)
     has_entity_name: bool = attr.ib(default=False)
     name: str | None = attr.ib(default=None)
-    options: EntityOptionsType = attr.ib(
-        default=None,
-        converter=attr.converters.default_if_none(factory=dict),  # type: ignore[misc]
-    )
+    options: _EntityOptions = attr.ib(default=None, converter=_EntityOptions)
     # As set by integration
     original_device_class: str | None = attr.ib(default=None)
     original_icon: str | None = attr.ib(default=None)
@@ -930,7 +951,7 @@ class EntityRegistry:
         If the domain options are set to None, they will be removed.
         """
         old = self.entities[entity_id]
-        new_options = {
+        new_options: dict[str, Mapping] = {
             key: value for key, value in old.options.items() if key != domain
         }
         if options is not None:
@@ -1010,7 +1031,7 @@ class EntityRegistry:
                 "id": entry.id,
                 "has_entity_name": entry.has_entity_name,
                 "name": entry.name,
-                "options": entry.options,
+                "options": entry.options.as_dict(),
                 "original_device_class": entry.original_device_class,
                 "original_icon": entry.original_icon,
                 "original_name": entry.original_name,
diff --git a/tests/helpers/test_entity_registry.py b/tests/helpers/test_entity_registry.py
index 79d6de32904..e3b91c46e18 100644
--- a/tests/helpers/test_entity_registry.py
+++ b/tests/helpers/test_entity_registry.py
@@ -747,6 +747,16 @@ async def test_update_entity_options(entity_registry: er.EntityRegistry) -> None
     assert entry.options == {}
     assert new_entry_1.options == {"light": {"minimum_brightness": 20}}
 
+    # Test it's not possible to modify the options
+    with pytest.raises(NotImplementedError):
+        new_entry_1.options["blah"] = {}
+    with pytest.raises(NotImplementedError):
+        new_entry_1.options["light"] = {}
+    with pytest.raises(TypeError):
+        new_entry_1.options["light"]["blah"] = 123
+    with pytest.raises(TypeError):
+        new_entry_1.options["light"]["minimum_brightness"] = 123
+
     entity_registry.async_update_entity_options(
         entry.entity_id, "light", {"minimum_brightness": 30}
     )
diff --git a/tests/syrupy.py b/tests/syrupy.py
index f18c11bf5d5..af34cb628fc 100644
--- a/tests/syrupy.py
+++ b/tests/syrupy.py
@@ -170,6 +170,7 @@ class HomeAssistantSnapshotSerializer(AmberDataSerializer):
                 "config_entry_id": ANY,
                 "device_id": ANY,
                 "id": ANY,
+                "options": data.options.as_dict(),
             }
         )
         serialized.pop("_partial_repr")