diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5a7da871..5b23040c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 0.4.0
 
 - Added `allow_with_comments` parameter for `no_empty_block` lint.
+- Added extension support for `avoid_using_api`
 - Added `exclude_entity` parameter for `prefer_match_file_name` lint.
   It is now possible to configure this lint to ignore `enum`,
   `extension` and `mixin` declarations via `analysis_options.yaml`.
diff --git a/lib/src/lints/avoid_using_api/avoid_using_api_linter.dart b/lib/src/lints/avoid_using_api/avoid_using_api_linter.dart
index 1b3f93c3..a89b8da0 100644
--- a/lib/src/lints/avoid_using_api/avoid_using_api_linter.dart
+++ b/lib/src/lints/avoid_using_api/avoid_using_api_linter.dart
@@ -245,5 +245,39 @@ class AvoidUsingApiLinter {
           );
       }
     });
+
+    context.registry.addMethodInvocation((node) {
+      final methodName = node.methodName.name;
+      if (methodName != identifier) return;
+
+      final enclosingElement = node.methodName.staticElement?.enclosingElement3;
+      if (enclosingElement is! ExtensionElement ||
+          enclosingElement.name != className) {
+        return;
+      }
+
+      final sourcePath = enclosingElement.librarySource.uri.toString();
+      if (!_matchesSource(sourcePath, source)) {
+        return;
+      }
+
+      reporter.atNode(node.methodName, entryCode);
+    });
+
+    context.registry.addPrefixedIdentifier((node) {
+      final propertyName = node.identifier.name;
+      if (propertyName != identifier) return;
+
+      final enclosingElement = node.identifier.staticElement?.enclosingElement3;
+      if (enclosingElement is! ExtensionElement ||
+          enclosingElement.name != className) {
+        return;
+      }
+
+      final sourcePath = enclosingElement.librarySource.uri.toString();
+      if (!_matchesSource(sourcePath, source)) return;
+
+      reporter.atNode(node.identifier, entryCode);
+    });
   }
 }
diff --git a/lint_test/avoid_using_api/external_source/lib/external_source.dart b/lint_test/avoid_using_api/external_source/lib/external_source.dart
index bd422108..144c6bd1 100644
--- a/lint_test/avoid_using_api/external_source/lib/external_source.dart
+++ b/lint_test/avoid_using_api/external_source/lib/external_source.dart
@@ -22,3 +22,9 @@ const test2 = 'Hello World';
 void test() {}
 
 int banned = 5;
+
+extension BannedExtension on int {
+  int banned() => this + 10;
+
+  int get bannedGetter => 10;
+}
diff --git a/lint_test/avoid_using_api/identifier_extension_source_ban/analysis_options.yaml b/lint_test/avoid_using_api/identifier_extension_source_ban/analysis_options.yaml
new file mode 100644
index 00000000..3a2b7c69
--- /dev/null
+++ b/lint_test/avoid_using_api/identifier_extension_source_ban/analysis_options.yaml
@@ -0,0 +1,18 @@
+analyzer:
+  plugins:
+    - ../../custom_lint
+
+custom_lint:
+  rules:
+    - avoid_using_api:
+      severity: warning
+      entries:
+        - class_name: BannedExtension
+          identifier: banned
+          source: package:external_source
+          reason: "Banned identifier from BannedExtension from package:external_source is not allowed"
+        - class_name: BannedExtension
+          identifier: bannedGetter
+          source: package:external_source
+          reason: "bannedGetter identifier from BannedExtension from package:external_source is not allowed"
+
diff --git a/lint_test/avoid_using_api/identifier_extension_source_ban/lib/identifier_extension_source_ban_test.dart b/lint_test/avoid_using_api/identifier_extension_source_ban/lib/identifier_extension_source_ban_test.dart
new file mode 100644
index 00000000..a3c0a8d0
--- /dev/null
+++ b/lint_test/avoid_using_api/identifier_extension_source_ban/lib/identifier_extension_source_ban_test.dart
@@ -0,0 +1,11 @@
+import 'package:external_source/external_source.dart';
+
+void extensionIdentifierBanTesting() {
+  const int a = 10;
+
+  // expect_lint: avoid_using_api
+  a.banned();
+
+  // expect_lint: avoid_using_api
+  a.bannedGetter;
+}
diff --git a/lint_test/avoid_using_api/identifier_extension_source_ban/pubspec.yaml b/lint_test/avoid_using_api/identifier_extension_source_ban/pubspec.yaml
new file mode 100644
index 00000000..012fa6ca
--- /dev/null
+++ b/lint_test/avoid_using_api/identifier_extension_source_ban/pubspec.yaml
@@ -0,0 +1,17 @@
+name: identifier_extension_source_ban
+description: A sample command-line application.
+version: 1.0.0
+publish_to: none
+
+environment:
+  sdk: ^3.7.2
+
+dependencies:
+  external_source:
+    path: ../external_source
+
+dev_dependencies:
+  lints: ^3.0.0
+  test: ^1.21.0
+  solid_lints:
+    path: ../../../