diff --git a/homeassistant/components/isy994/const.py b/homeassistant/components/isy994/const.py
index 3b129776b31..30059c68c10 100644
--- a/homeassistant/components/isy994/const.py
+++ b/homeassistant/components/isy994/const.py
@@ -193,6 +193,7 @@ UOM_HVAC_MODE_INSTEON = "98"
 UOM_FAN_MODES = "99"
 UOM_INDEX = "25"
 UOM_ON_OFF = "2"
+UOM_PERCENTAGE = "51"
 
 # Do not use the Home Assistant consts for the states here - we're matching exact API
 # responses, not using them for Home Assistant states
@@ -369,7 +370,7 @@ UOM_FRIENDLY_NAME = {
     "48": SPEED_MILES_PER_HOUR,
     "49": SPEED_METERS_PER_SECOND,
     "50": "Ω",
-    "51": PERCENTAGE,
+    UOM_PERCENTAGE: PERCENTAGE,
     "52": MASS_POUNDS,
     "53": "pf",
     "54": CONCENTRATION_PARTS_PER_MILLION,
diff --git a/homeassistant/components/isy994/cover.py b/homeassistant/components/isy994/cover.py
index 51a26585778..bdc2bc7f6d4 100644
--- a/homeassistant/components/isy994/cover.py
+++ b/homeassistant/components/isy994/cover.py
@@ -53,7 +53,7 @@ class ISYCoverEntity(ISYNodeEntity, CoverEntity):
         if self._node.status == ISY_VALUE_UNKNOWN:
             return None
         if self._node.uom == UOM_8_BIT_RANGE:
-            return int(self._node.status * 100 / 255)
+            return round(self._node.status * 100.0 / 255.0)
         return sorted((0, self._node.status, 100))[1]
 
     @property
@@ -83,7 +83,7 @@ class ISYCoverEntity(ISYNodeEntity, CoverEntity):
         """Move the cover to a specific position."""
         position = kwargs[ATTR_POSITION]
         if self._node.uom == UOM_8_BIT_RANGE:
-            position = int(position * 255 / 100)
+            position = round(position * 255.0 / 100.0)
         if not self._node.turn_on(val=position):
             _LOGGER.error("Unable to set cover position")
 
diff --git a/homeassistant/components/isy994/light.py b/homeassistant/components/isy994/light.py
index 7f94c68714d..7ff44863f6b 100644
--- a/homeassistant/components/isy994/light.py
+++ b/homeassistant/components/isy994/light.py
@@ -17,6 +17,7 @@ from .const import (
     CONF_RESTORE_LIGHT_STATE,
     DOMAIN as ISY994_DOMAIN,
     ISY994_NODES,
+    UOM_PERCENTAGE,
 )
 from .entity import ISYNodeEntity
 from .helpers import migrate_old_unique_ids
@@ -65,6 +66,9 @@ class ISYLightEntity(ISYNodeEntity, LightEntity, RestoreEntity):
         """Get the brightness of the ISY994 light."""
         if self._node.status == ISY_VALUE_UNKNOWN:
             return None
+        # Special Case for ISY Z-Wave Devices using % instead of 0-255:
+        if self._node.uom == UOM_PERCENTAGE:
+            return round(self._node.status * 255.0 / 100.0)
         return int(self._node.status)
 
     def turn_off(self, **kwargs) -> None:
@@ -76,7 +80,10 @@ class ISYLightEntity(ISYNodeEntity, LightEntity, RestoreEntity):
     def on_update(self, event: object) -> None:
         """Save brightness in the update event from the ISY994 Node."""
         if self._node.status not in (0, ISY_VALUE_UNKNOWN):
-            self._last_brightness = self._node.status
+            if self._node.uom == UOM_PERCENTAGE:
+                self._last_brightness = round(self._node.status * 255.0 / 100.0)
+            else:
+                self._last_brightness = self._node.status
         super().on_update(event)
 
     # pylint: disable=arguments-differ
@@ -84,6 +91,9 @@ class ISYLightEntity(ISYNodeEntity, LightEntity, RestoreEntity):
         """Send the turn on command to the ISY994 light device."""
         if self._restore_light_state and brightness is None and self._last_brightness:
             brightness = self._last_brightness
+        # Special Case for ISY Z-Wave Devices using % instead of 0-255:
+        if brightness is not None and self._node.uom == UOM_PERCENTAGE:
+            brightness = round(brightness * 100.0 / 255.0)
         if not self._node.turn_on(val=brightness):
             _LOGGER.debug("Unable to turn on light")