diff --git a/homeassistant/components/harmony/config_flow.py b/homeassistant/components/harmony/config_flow.py
index 576451ef2d6..9142eed2dba 100644
--- a/homeassistant/components/harmony/config_flow.py
+++ b/homeassistant/components/harmony/config_flow.py
@@ -86,6 +86,9 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         parsed_url = urlparse(discovery_info[ssdp.ATTR_SSDP_LOCATION])
         friendly_name = discovery_info[ssdp.ATTR_UPNP_FRIENDLY_NAME]
 
+        if self._host_already_configured(parsed_url.hostname):
+            return self.async_abort(reason="already_configured")
+
         # pylint: disable=no-member
         self.context["title_placeholders"] = {"name": friendly_name}
 
@@ -158,6 +161,13 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
         return self.async_create_entry(title=validated[CONF_NAME], data=data)
 
+    def _host_already_configured(self, host):
+        """See if we already have a harmony entry matching the host."""
+        for entry in self._async_current_entries():
+            if entry.data[CONF_HOST] == host:
+                return True
+        return False
+
 
 def _options_from_user_input(user_input):
     options = {}
diff --git a/tests/components/harmony/test_config_flow.py b/tests/components/harmony/test_config_flow.py
index 0228983ef9d..d159a0f025f 100644
--- a/tests/components/harmony/test_config_flow.py
+++ b/tests/components/harmony/test_config_flow.py
@@ -145,6 +145,30 @@ async def test_form_ssdp(hass):
     assert len(mock_setup_entry.mock_calls) == 1
 
 
+async def test_form_ssdp_aborts_before_checking_remoteid_if_host_known(hass):
+    """Test we abort without connecting if the host is already known."""
+    await setup.async_setup_component(hass, "persistent_notification", {})
+    config_entry = MockConfigEntry(
+        domain=DOMAIN, data={"host": "2.2.2.2", "name": "any"},
+    )
+    config_entry.add_to_hass(hass)
+
+    harmonyapi = _get_mock_harmonyapi(connect=True)
+
+    with patch(
+        "homeassistant.components.harmony.util.HarmonyAPI", return_value=harmonyapi,
+    ):
+        result = await hass.config_entries.flow.async_init(
+            DOMAIN,
+            context={"source": config_entries.SOURCE_SSDP},
+            data={
+                "friendlyName": "Harmony Hub",
+                "ssdp_location": "http://2.2.2.2:8088/description",
+            },
+        )
+    assert result["type"] == "abort"
+
+
 async def test_form_cannot_connect(hass):
     """Test we handle cannot connect error."""
     result = await hass.config_entries.flow.async_init(