diff --git a/commitizen/cz/customize/customize.py b/commitizen/cz/customize/customize.py
index 8fcc63fac..b3d2ab81a 100644
--- a/commitizen/cz/customize/customize.py
+++ b/commitizen/cz/customize/customize.py
@@ -29,6 +29,17 @@ class CustomizeCommitsCz(BaseCommitizen):
     bump_map = defaults.BUMP_MAP
     bump_map_major_version_zero = defaults.BUMP_MAP_MAJOR_VERSION_ZERO
     change_type_order = defaults.CHANGE_TYPE_ORDER
+    # A conventional-commits-style default so that ``cz_customize`` users who
+    # configure ``changelog_pattern`` (and optionally ``change_type_map`` /
+    # ``change_type_order``) but no explicit ``commit_parser`` still get a
+    # changelog grouped by change type. The conventional prefix is optional,
+    # so non-conforming subjects remain included as ungrouped messages.
+    # Users with a different commit format can still override this via
+    # ``customize.commit_parser`` (#466).
+    commit_parser = (
+        r"^((?P<change_type>[\w-]+)(?:\((?P<scope>[^()\r\n]*)\))?"
+        r"(?P<breaking>!)?:\s+)?(?P<message>.+)$"
+    )
 
     def __init__(self, config: BaseConfig) -> None:
         super().__init__(config)
diff --git a/tests/test_cz_customize.py b/tests/test_cz_customize.py
index 311eea19a..aff957c22 100644
--- a/tests/test_cz_customize.py
+++ b/tests/test_cz_customize.py
@@ -591,6 +591,120 @@ def test_commit_parser_unicode(config_with_unicode):
     )
 
 
+def test_commit_parser_default_extracts_change_type():
+    """Regression test for #466: when ``customize.commit_parser`` is not set,
+    the default must still extract a ``change_type`` named group so that the
+    changelog can be grouped by type (e.g. ``### Feat``, ``### Fix``).
+    Previously the default was ``r"(?P<message>.*)"`` -- inherited from
+    ``BaseCommitizen`` -- which left every commit ungrouped.
+    """
+    import re
+
+    config = BaseConfig()
+    config.settings.update(
+        {
+            "name": "cz_customize",
+            "customize": {
+                # No ``commit_parser`` provided -- exercises the new default.
+                "changelog_pattern": r"^(feat|fix|chore)(\(.+\))?(!)?",
+            },
+        }
+    )
+    cz = CustomizeCommitsCz(config)
+
+    pattern = re.compile(cz.commit_parser, re.MULTILINE)
+
+    feat = pattern.match("feat(scope): a feature")
+    assert feat is not None
+    assert feat.group("change_type") == "feat"
+    assert feat.group("scope") == "scope"
+    assert feat.group("breaking") is None
+    assert feat.group("message") == "a feature"
+
+    breaking = pattern.match("fix!: breaking fix")
+    assert breaking is not None
+    assert breaking.group("change_type") == "fix"
+    assert breaking.group("breaking") == "!"
+    assert breaking.group("message") == "breaking fix"
+
+    no_scope = pattern.match("chore: tidy up")
+    assert no_scope is not None
+    assert no_scope.group("change_type") == "chore"
+    assert no_scope.group("scope") is None
+    assert no_scope.group("message") == "tidy up"
+
+
+def test_commit_parser_default_keeps_non_conforming_subjects():
+    import re
+
+    config = BaseConfig()
+    config.settings.update(
+        {
+            "name": "cz_customize",
+            "customize": {
+                # No ``commit_parser`` provided -- exercises the new default.
+                "changelog_pattern": r".*",
+            },
+        }
+    )
+    cz = CustomizeCommitsCz(config)
+
+    pattern = re.compile(cz.commit_parser, re.MULTILINE)
+
+    cases = [
+        (
+            "bug fix: do stuff",
+            {
+                "change_type": None,
+                "scope": None,
+                "breaking": None,
+                "message": "bug fix: do stuff",
+            },
+        ),
+        (
+            "ticket-123 do stuff",
+            {
+                "change_type": None,
+                "scope": None,
+                "breaking": None,
+                "message": "ticket-123 do stuff",
+            },
+        ),
+        (
+            "✨ feature: shiny",
+            {
+                "change_type": None,
+                "scope": None,
+                "breaking": None,
+                "message": "✨ feature: shiny",
+            },
+        ),
+        (
+            "feat: ok",
+            {
+                "change_type": "feat",
+                "scope": None,
+                "breaking": None,
+                "message": "ok",
+            },
+        ),
+        (
+            "feat(api)!: bang",
+            {
+                "change_type": "feat",
+                "scope": "api",
+                "breaking": "!",
+                "message": "bang",
+            },
+        ),
+    ]
+
+    for subject, expected_groups in cases:
+        match = pattern.match(subject)
+        assert match is not None
+        assert match.groupdict() == expected_groups
+
+
 def test_changelog_pattern(config):
     cz = CustomizeCommitsCz(config)
     assert cz.changelog_pattern == "^(feature|bug fix)?(!)?"