diff --git a/homeassistant/components/filesize/__init__.py b/homeassistant/components/filesize/__init__.py
index 90d2af5d52a..f74efefbcad 100644
--- a/homeassistant/components/filesize/__init__.py
+++ b/homeassistant/components/filesize/__init__.py
@@ -2,18 +2,39 @@
 
 from __future__ import annotations
 
+import pathlib
+
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import CONF_FILE_PATH
 from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import ConfigEntryNotReady
 
 from .const import PLATFORMS
 from .coordinator import FileSizeCoordinator
 
+FileSizeConfigEntry = ConfigEntry[FileSizeCoordinator]
 
-async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+
+def _get_full_path(hass: HomeAssistant, path: str) -> pathlib.Path:
+    """Check if path is valid, allowed and return full path."""
+    get_path = pathlib.Path(path)
+    if not hass.config.is_allowed_path(path):
+        raise ConfigEntryNotReady(f"Filepath {path} is not valid or allowed")
+
+    if not get_path.exists() or not get_path.is_file():
+        raise ConfigEntryNotReady(f"Can not access file {path}")
+
+    return get_path.absolute()
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: FileSizeConfigEntry) -> bool:
     """Set up from a config entry."""
-    coordinator = FileSizeCoordinator(hass, entry.data[CONF_FILE_PATH])
+    path = await hass.async_add_executor_job(
+        _get_full_path, hass, entry.data[CONF_FILE_PATH]
+    )
+    coordinator = FileSizeCoordinator(hass, path)
     await coordinator.async_config_entry_first_refresh()
+    entry.runtime_data = coordinator
 
     await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
     return True
diff --git a/homeassistant/components/filesize/coordinator.py b/homeassistant/components/filesize/coordinator.py
index 2e59e922801..dcb7486209b 100644
--- a/homeassistant/components/filesize/coordinator.py
+++ b/homeassistant/components/filesize/coordinator.py
@@ -19,7 +19,7 @@ _LOGGER = logging.getLogger(__name__)
 class FileSizeCoordinator(DataUpdateCoordinator[dict[str, int | float | datetime]]):
     """Filesize coordinator."""
 
-    def __init__(self, hass: HomeAssistant, unresolved_path: str) -> None:
+    def __init__(self, hass: HomeAssistant, path: pathlib.Path) -> None:
         """Initialize filesize coordinator."""
         super().__init__(
             hass,
@@ -28,28 +28,12 @@ class FileSizeCoordinator(DataUpdateCoordinator[dict[str, int | float | datetime
             update_interval=timedelta(seconds=60),
             always_update=False,
         )
-        self._unresolved_path = unresolved_path
-        self._path: pathlib.Path | None = None
-
-    def _get_full_path(self) -> pathlib.Path:
-        """Check if path is valid, allowed and return full path."""
-        path = self._unresolved_path
-        get_path = pathlib.Path(path)
-        if not self.hass.config.is_allowed_path(path):
-            raise UpdateFailed(f"Filepath {path} is not valid or allowed")
-
-        if not get_path.exists() or not get_path.is_file():
-            raise UpdateFailed(f"Can not access file {path}")
-
-        return get_path.absolute()
+        self.path: pathlib.Path = path
 
     def _update(self) -> os.stat_result:
         """Fetch file information."""
-        if not self._path:
-            self._path = self._get_full_path()
-
         try:
-            return self._path.stat()
+            return self.path.stat()
         except OSError as error:
             raise UpdateFailed(f"Can not retrieve file statistics {error}") from error
 
diff --git a/homeassistant/components/filesize/sensor.py b/homeassistant/components/filesize/sensor.py
index 761513b1f48..71a4e50edfe 100644
--- a/homeassistant/components/filesize/sensor.py
+++ b/homeassistant/components/filesize/sensor.py
@@ -4,7 +4,6 @@ from __future__ import annotations
 
 from datetime import datetime
 import logging
-import pathlib
 
 from homeassistant.components.sensor import (
     SensorDeviceClass,
@@ -12,13 +11,13 @@ from homeassistant.components.sensor import (
     SensorEntityDescription,
     SensorStateClass,
 )
-from homeassistant.config_entries import ConfigEntry
-from homeassistant.const import CONF_FILE_PATH, EntityCategory, UnitOfInformation
+from homeassistant.const import EntityCategory, UnitOfInformation
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers.device_registry import DeviceEntryType, DeviceInfo
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
 
+from . import FileSizeConfigEntry
 from .const import DOMAIN
 from .coordinator import FileSizeCoordinator
 
@@ -53,20 +52,12 @@ SENSOR_TYPES = (
 
 async def async_setup_entry(
     hass: HomeAssistant,
-    entry: ConfigEntry,
+    entry: FileSizeConfigEntry,
     async_add_entities: AddEntitiesCallback,
 ) -> None:
     """Set up the platform from config entry."""
-
-    path = entry.data[CONF_FILE_PATH]
-    get_path = await hass.async_add_executor_job(pathlib.Path, path)
-    fullpath = str(get_path.absolute())
-
-    coordinator = FileSizeCoordinator(hass, fullpath)
-    await coordinator.async_config_entry_first_refresh()
-
     async_add_entities(
-        FilesizeEntity(description, fullpath, entry.entry_id, coordinator)
+        FilesizeEntity(description, entry.entry_id, entry.runtime_data)
         for description in SENSOR_TYPES
     )
 
@@ -79,13 +70,12 @@ class FilesizeEntity(CoordinatorEntity[FileSizeCoordinator], SensorEntity):
     def __init__(
         self,
         description: SensorEntityDescription,
-        path: str,
         entry_id: str,
         coordinator: FileSizeCoordinator,
     ) -> None:
         """Initialize the Filesize sensor."""
         super().__init__(coordinator)
-        base_name = path.split("/")[-1]
+        base_name = str(coordinator.path.absolute()).rsplit("/", maxsplit=1)[-1]
         self._attr_unique_id = (
             entry_id if description.key == "file" else f"{entry_id}-{description.key}"
         )