diff --git a/esphome/config_validation.py b/esphome/config_validation.py
index 2bb45487fa..8df74ba861 100644
--- a/esphome/config_validation.py
+++ b/esphome/config_validation.py
@@ -296,9 +296,11 @@ def icon(value):
     value = string_strict(value)
     if not value:
         return value
-    if value.startswith("mdi:"):
+    if re.match("^[\\w\\-]+:[\\w\\-]+$", value):
         return value
-    raise Invalid('Icons should start with prefix "mdi:"')
+    raise Invalid(
+        'Icons must match the format "[icon pack]:[icon]", e.g. "mdi:home-assistant"'
+    )
 
 
 def boolean(value):
diff --git a/tests/unit_tests/test_config_validation.py b/tests/unit_tests/test_config_validation.py
index 16cfb16e94..9e9af52d00 100644
--- a/tests/unit_tests/test_config_validation.py
+++ b/tests/unit_tests/test_config_validation.py
@@ -66,7 +66,7 @@ def test_string_string__invalid(value):
         config_validation.string_strict(value)
 
 
-@given(builds(lambda v: "mdi:" + v, text()))
+@given(builds(lambda v: "mdi:" + v, text(alphabet=string.ascii_letters + string.digits + "-_", min_size=1, max_size=20)))
 @example("")
 def test_icon__valid(value):
     actual = config_validation.icon(value)
@@ -75,7 +75,7 @@ def test_icon__valid(value):
 
 
 def test_icon__invalid():
-    with pytest.raises(Invalid, match="Icons should start with prefix"):
+    with pytest.raises(Invalid, match="Icons must match the format "):
         config_validation.icon("foo")