diff --git a/news/9330.bugfix.rst b/news/9330.bugfix.rst
new file mode 100644
index 00000000000..4cbd4192b89
--- /dev/null
+++ b/news/9330.bugfix.rst
@@ -0,0 +1 @@
+``pip config`` normalizes names, converting underscores into dashes
\ No newline at end of file
diff --git a/src/pip/_internal/configuration.py b/src/pip/_internal/configuration.py
index a8092d1ae06..a2b0607c5dc 100644
--- a/src/pip/_internal/configuration.py
+++ b/src/pip/_internal/configuration.py
@@ -142,13 +142,16 @@ def items(self) -> Iterable[Tuple[str, Any]]:
 
     def get_value(self, key: str) -> Any:
         """Get a value from the configuration."""
+        orig_key = key
+        key = _normalize_name(key)
         try:
             return self._dictionary[key]
         except KeyError:
-            raise ConfigurationError(f"No such key - {key}")
+            raise ConfigurationError(f"No such key - {orig_key}")
 
     def set_value(self, key: str, value: Any) -> None:
         """Modify a value in the configuration."""
+        key = _normalize_name(key)
         self._ensure_have_load_only()
 
         assert self.load_only
@@ -167,11 +170,13 @@ def set_value(self, key: str, value: Any) -> None:
 
     def unset_value(self, key: str) -> None:
         """Unset a value in the configuration."""
+        orig_key = key
+        key = _normalize_name(key)
         self._ensure_have_load_only()
 
         assert self.load_only
         if key not in self._config[self.load_only]:
-            raise ConfigurationError(f"No such key - {key}")
+            raise ConfigurationError(f"No such key - {orig_key}")
 
         fname, parser = self._get_parser_to_modify()
 
diff --git a/tests/unit/test_configuration.py b/tests/unit/test_configuration.py
index 788d32b9b76..22ea983958c 100644
--- a/tests/unit/test_configuration.py
+++ b/tests/unit/test_configuration.py
@@ -185,12 +185,8 @@ class TestConfigurationModification(ConfigurationMixin):
     def test_no_specific_given_modification(self) -> None:
         self.configuration.load()
 
-        try:
+        with pytest.raises(ConfigurationError):
             self.configuration.set_value("test.hello", "10")
-        except ConfigurationError:
-            pass
-        else:
-            assert False, "Should have raised an error."
 
     def test_site_modification(self) -> None:
         self.configuration.load_only = kinds.SITE
@@ -241,3 +237,16 @@ def test_global_modification(self) -> None:
         # get the path to user config file
         assert mymock.call_count == 1
         assert mymock.call_args[0][0] == (get_configuration_files()[kinds.GLOBAL][-1])
+
+    def test_normalization(self) -> None:
+        # underscores and dashes can be used interchangeably.
+        # internally, underscores get converted into dashes before reading/writing file
+        self.configuration.load_only = kinds.GLOBAL
+        self.configuration.load()
+        self.configuration.set_value("global.index-url", "example.org")
+        assert self.configuration.get_value("global.index_url") == "example.org"
+        assert self.configuration.get_value("global.index-url") == "example.org"
+        self.configuration.unset_value("global.index-url")
+        pat = r"^No such key - global\.index-url$"
+        with pytest.raises(ConfigurationError, match=pat):
+            self.configuration.get_value("global.index-url")