diff --git a/homeassistant/components/cert_expiry/config_flow.py b/homeassistant/components/cert_expiry/config_flow.py
index 43931fe5830..78450d247b9 100644
--- a/homeassistant/components/cert_expiry/config_flow.py
+++ b/homeassistant/components/cert_expiry/config_flow.py
@@ -1,5 +1,7 @@
 """Config flow for the Cert Expiry platform."""
+import logging
 import socket
+import ssl
 import voluptuous as vol
 
 from homeassistant import config_entries
@@ -9,6 +11,8 @@ from homeassistant.core import HomeAssistant, callback
 from .const import DOMAIN, DEFAULT_PORT, DEFAULT_NAME
 from .helper import get_cert
 
+_LOGGER = logging.getLogger(__name__)
+
 
 @callback
 def certexpiry_entries(hass: HomeAssistant):
@@ -39,17 +43,28 @@ class CertexpiryConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
     async def _test_connection(self, user_input=None):
         """Test connection to the server and try to get the certtificate."""
+        host = user_input[CONF_HOST]
         try:
             await self.hass.async_add_executor_job(
-                get_cert, user_input[CONF_HOST], user_input.get(CONF_PORT, DEFAULT_PORT)
+                get_cert, host, user_input.get(CONF_PORT, DEFAULT_PORT)
             )
             return True
         except socket.gaierror:
+            _LOGGER.error("Host cannot be resolved: %s", host)
             self._errors[CONF_HOST] = "resolve_failed"
         except socket.timeout:
+            _LOGGER.error("Timed out connecting to %s", host)
             self._errors[CONF_HOST] = "connection_timeout"
-        except OSError:
-            self._errors[CONF_HOST] = "certificate_fetch_failed"
+        except ssl.CertificateError as err:
+            if "doesn't match" in err.args[0]:
+                _LOGGER.error("Certificate does not match host: %s", host)
+                self._errors[CONF_HOST] = "wrong_host"
+            else:
+                _LOGGER.error("Certificate could not be validated: %s", host)
+                self._errors[CONF_HOST] = "certificate_error"
+        except ssl.SSLError:
+            _LOGGER.error("Certificate could not be validated: %s", host)
+            self._errors[CONF_HOST] = "certificate_error"
         return False
 
     async def async_step_user(self, user_input=None):
diff --git a/homeassistant/components/cert_expiry/sensor.py b/homeassistant/components/cert_expiry/sensor.py
index 2d578ef2c3b..3022c7bd42b 100644
--- a/homeassistant/components/cert_expiry/sensor.py
+++ b/homeassistant/components/cert_expiry/sensor.py
@@ -70,6 +70,7 @@ class SSLCertificate(Entity):
         self._name = sensor_name
         self._state = None
         self._available = False
+        self._valid = False
 
     @property
     def name(self):
@@ -122,16 +123,17 @@ class SSLCertificate(Entity):
         except socket.gaierror:
             _LOGGER.error("Cannot resolve hostname: %s", self.server_name)
             self._available = False
+            self._valid = False
             return
         except socket.timeout:
             _LOGGER.error("Connection timeout with server: %s", self.server_name)
             self._available = False
+            self._valid = False
             return
-        except OSError:
-            _LOGGER.error(
-                "Cannot fetch certificate from %s", self.server_name, exc_info=1
-            )
-            self._available = False
+        except (ssl.CertificateError, ssl.SSLError):
+            self._available = True
+            self._state = 0
+            self._valid = False
             return
 
         ts_seconds = ssl.cert_time_to_seconds(cert["notAfter"])
@@ -139,3 +141,11 @@ class SSLCertificate(Entity):
         expiry = timestamp - datetime.today()
         self._available = True
         self._state = expiry.days
+        self._valid = True
+
+    @property
+    def device_state_attributes(self):
+        """Return additional sensor state attributes."""
+        attr = {"is_valid": self._valid}
+
+        return attr
diff --git a/homeassistant/components/cert_expiry/strings.json b/homeassistant/components/cert_expiry/strings.json
index 3e2fea2342e..e5e670d214f 100644
--- a/homeassistant/components/cert_expiry/strings.json
+++ b/homeassistant/components/cert_expiry/strings.json
@@ -15,7 +15,8 @@
             "host_port_exists": "This host and port combination is already configured",
             "resolve_failed": "This host can not be resolved",
             "connection_timeout": "Timeout when connecting to this host",
-            "certificate_fetch_failed": "Can not fetch certificate from this host and port combination"
+            "certificate_error": "Certificate could not be validated",
+            "wrong_host": "Certificate does not match hostname"
         },
         "abort": {
             "host_port_exists": "This host and port combination is already configured"
diff --git a/tests/components/cert_expiry/test_config_flow.py b/tests/components/cert_expiry/test_config_flow.py
index 988f3e97106..3754551c230 100644
--- a/tests/components/cert_expiry/test_config_flow.py
+++ b/tests/components/cert_expiry/test_config_flow.py
@@ -1,5 +1,6 @@
 """Tests for the Cert Expiry config flow."""
 import pytest
+import ssl
 import socket
 from unittest.mock import patch
 
@@ -131,7 +132,22 @@ async def test_abort_on_socket_failed(hass):
         assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
         assert result["errors"] == {CONF_HOST: "connection_timeout"}
 
-    with patch("socket.create_connection", side_effect=OSError()):
+    with patch(
+        "socket.create_connection",
+        side_effect=ssl.CertificateError(f"{HOST} doesn't match somethingelse.com"),
+    ):
         result = await flow.async_step_user({CONF_HOST: HOST})
         assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
-        assert result["errors"] == {CONF_HOST: "certificate_fetch_failed"}
+        assert result["errors"] == {CONF_HOST: "wrong_host"}
+
+    with patch(
+        "socket.create_connection", side_effect=ssl.CertificateError("different error")
+    ):
+        result = await flow.async_step_user({CONF_HOST: HOST})
+        assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
+        assert result["errors"] == {CONF_HOST: "certificate_error"}
+
+    with patch("socket.create_connection", side_effect=ssl.SSLError()):
+        result = await flow.async_step_user({CONF_HOST: HOST})
+        assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
+        assert result["errors"] == {CONF_HOST: "certificate_error"}