diff --git a/README.md b/README.md
index 494f807..6497084 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,7 @@ This repository contains reusable composite actions for CI/CD workflows across o
 | [Enforce Flutter Version Constraint](./enforce-flutter-version) | Scans all pubspec.yaml files to ensure they use the required Flutter SDK constraint. | `rodydavis/shared-actions/enforce-flutter-version@main` |
 | [Run Buildifier](./run-buildifier) | Downloads and runs buildifier on Starlark files. | `rodydavis/shared-actions/run-buildifier@main` |
 | [Setup Bazel (Bazelisk)](./setup-bazel) | Installs Node, Bazelisk, and configures Git for private SSH dependencies. | `rodydavis/shared-actions/setup-bazel@main` |
+| [Setup Flutter](./setup-flutter) | Cross-platform setup for Flutter with caching on macOS, Windows, and Linux. | `rodydavis/shared-actions/setup-flutter@main` |
 
 <!-- END_ACTIONS_TABLE -->
 
diff --git a/setup-flutter/README.md b/setup-flutter/README.md
new file mode 100644
index 0000000..df0e96f
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+++ b/setup-flutter/README.md
@@ -0,0 +1,42 @@
+# Setup Flutter
+
+Cross-platform composite action to set up the Flutter SDK with automated caching on macOS, Windows, and Linux. Supports local Git mirrors with automatic fallback to upstream GitHub.
+
+## Features
+
+- **Multi-OS Support**: Native setup for macOS (Apple Silicon & Intel), Windows (PowerShell), and Linux.
+- **Git Mirror & Fallback**: Clones from local Gitea Flutter mirror (`https://git.rodydavis.dev/rodydavis/flutter.git`) with automatic fallback to `https://github.com/flutter/flutter.git`.
+- **SDK Caching**: Uses `actions/cache@v3` to cache the full Flutter SDK directory across workflow runs based on OS, CPU architecture, and version.
+- **Desktop Windowing**: Automatically configures desktop windowing support and exports Flutter to `$GITHUB_PATH`.
+
+## Inputs
+
+| Name | Description | Required | Default |
+| :--- | :--- | :--- | :--- |
+| `version` | Flutter channel, tag, or branch (e.g., `master`, `stable`, `3.29.0`). | No | `master` |
+| `mirror_url` | Git repository URL for Flutter SDK mirror. | No | `https://git.rodydavis.dev/rodydavis/flutter.git` |
+| `git_token` | Gitea token for authenticated git mirror access. | No | `''` |
+| `cache` | Enable Flutter SDK caching across CI runs. | No | `true` |
+| `enable_windowing` | Enable desktop windowing and platform configs. | No | `true` |
+
+## Example Usage
+
+### Basic Usage (Master Channel)
+
+```yaml
+- name: Set up Flutter
+  uses: rodydavis/shared-actions/setup-flutter@main
+  with:
+    version: master
+    git_token: ${{ secrets.GIT_TOKEN }}
+```
+
+### Specific Version Tag with Caching
+
+```yaml
+- name: Set up Flutter 3.29.0
+  uses: rodydavis/shared-actions/setup-flutter@main
+  with:
+    version: '3.29.0'
+    cache: 'true'
+```