diff --git a/homeassistant/components/overkiz/config_flow.py b/homeassistant/components/overkiz/config_flow.py
index d3ab9722fca..eac749f1bc0 100644
--- a/homeassistant/components/overkiz/config_flow.py
+++ b/homeassistant/components/overkiz/config_flow.py
@@ -9,6 +9,7 @@ from pyoverkiz.client import OverkizClient
 from pyoverkiz.const import SUPPORTED_SERVERS
 from pyoverkiz.exceptions import (
     BadCredentialsException,
+    CozyTouchBadCredentialsException,
     MaintenanceException,
     TooManyAttemptsBannedException,
     TooManyRequestsException,
@@ -67,6 +68,7 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
     ) -> FlowResult:
         """Handle the initial step via config flow."""
         errors = {}
+        description_placeholders = {}
 
         if user_input:
             self._default_user = user_input[CONF_USERNAME]
@@ -76,8 +78,16 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
                 await self.async_validate_input(user_input)
             except TooManyRequestsException:
                 errors["base"] = "too_many_requests"
-            except BadCredentialsException:
-                errors["base"] = "invalid_auth"
+            except BadCredentialsException as exception:
+                # If authentication with CozyTouch auth server is valid, but token is invalid
+                # for Overkiz API server, the hardware is not supported.
+                if user_input[CONF_HUB] == "atlantic_cozytouch" and not isinstance(
+                    exception, CozyTouchBadCredentialsException
+                ):
+                    description_placeholders["unsupported_device"] = "CozyTouch"
+                    errors["base"] = "unsupported_hardware"
+                else:
+                    errors["base"] = "invalid_auth"
             except (TimeoutError, ClientError):
                 errors["base"] = "cannot_connect"
             except MaintenanceException:
@@ -85,7 +95,10 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
             except TooManyAttemptsBannedException:
                 errors["base"] = "too_many_attempts"
             except UnknownUserException:
-                errors["base"] = "unknown_user"
+                # Somfy Protect accounts are not supported since they don't use
+                # the Overkiz API server. Login will return unknown user.
+                description_placeholders["unsupported_device"] = "Somfy Protect"
+                errors["base"] = "unsupported_hardware"
             except Exception as exception:  # pylint: disable=broad-except
                 errors["base"] = "unknown"
                 LOGGER.exception(exception)
@@ -129,6 +142,7 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
                     ),
                 }
             ),
+            description_placeholders=description_placeholders,
             errors=errors,
         )
 
diff --git a/homeassistant/components/overkiz/strings.json b/homeassistant/components/overkiz/strings.json
index ecc0329eb2a..440ed154cfe 100644
--- a/homeassistant/components/overkiz/strings.json
+++ b/homeassistant/components/overkiz/strings.json
@@ -19,7 +19,7 @@
       "too_many_attempts": "Too many attempts with an invalid token, temporarily banned",
       "too_many_requests": "Too many requests, try again later",
       "unknown": "[%key:common::config_flow::error::unknown%]",
-      "unknown_user": "Unknown user. Somfy Protect accounts are not supported by this integration."
+      "unsupported_hardware": "Your {unsupported_device} hardware is not supported by this integration."
     },
     "abort": {
       "already_configured": "[%key:common::config_flow::abort::already_configured_account%]",
diff --git a/homeassistant/components/overkiz/translations/en.json b/homeassistant/components/overkiz/translations/en.json
index 9c8ad538695..2c534a64cb6 100644
--- a/homeassistant/components/overkiz/translations/en.json
+++ b/homeassistant/components/overkiz/translations/en.json
@@ -12,7 +12,7 @@
             "too_many_attempts": "Too many attempts with an invalid token, temporarily banned",
             "too_many_requests": "Too many requests, try again later",
             "unknown": "Unexpected error",
-            "unknown_user": "Unknown user. Somfy Protect accounts are not supported by this integration."
+            "unsupported_hardware": "Your {unsupported_device} hardware is not supported by this integration."
         },
         "flow_title": "Gateway: {gateway_id}",
         "step": {
diff --git a/tests/components/overkiz/test_config_flow.py b/tests/components/overkiz/test_config_flow.py
index 940da7b39c2..dc50896626d 100644
--- a/tests/components/overkiz/test_config_flow.py
+++ b/tests/components/overkiz/test_config_flow.py
@@ -27,6 +27,7 @@ TEST_PASSWORD = "test-password"
 TEST_PASSWORD2 = "test-password2"
 TEST_HUB = "somfy_europe"
 TEST_HUB2 = "hi_kumo_europe"
+TEST_HUB_COZYTOUCH = "atlantic_cozytouch"
 TEST_GATEWAY_ID = "1234-5678-9123"
 TEST_GATEWAY_ID2 = "4321-5678-9123"
 
@@ -89,7 +90,7 @@ async def test_form(hass: HomeAssistant) -> None:
         (ClientError, "cannot_connect"),
         (MaintenanceException, "server_in_maintenance"),
         (TooManyAttemptsBannedException, "too_many_attempts"),
-        (UnknownUserException, "unknown_user"),
+        (UnknownUserException, "unsupported_hardware"),
         (Exception, "unknown"),
     ],
 )
@@ -112,6 +113,35 @@ async def test_form_invalid_auth(
     assert result2["errors"] == {"base": error}
 
 
+@pytest.mark.parametrize(
+    "side_effect, error",
+    [
+        (BadCredentialsException, "unsupported_hardware"),
+    ],
+)
+async def test_form_invalid_cozytouch_auth(
+    hass: HomeAssistant, side_effect: Exception, error: str
+) -> None:
+    """Test we handle invalid auth from CozyTouch."""
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": config_entries.SOURCE_USER}
+    )
+
+    with patch("pyoverkiz.client.OverkizClient.login", side_effect=side_effect):
+        result2 = await hass.config_entries.flow.async_configure(
+            result["flow_id"],
+            {
+                "username": TEST_EMAIL,
+                "password": TEST_PASSWORD,
+                "hub": TEST_HUB_COZYTOUCH,
+            },
+        )
+
+    assert result["step_id"] == config_entries.SOURCE_USER
+    assert result["type"] == data_entry_flow.FlowResultType.FORM
+    assert result2["errors"] == {"base": error}
+
+
 async def test_abort_on_duplicate_entry(hass: HomeAssistant) -> None:
     """Test config flow aborts Config Flow on duplicate entries."""
     MockConfigEntry(