diff --git a/bin/internal/shared.sh b/bin/internal/shared.sh
--- a/bin/internal/shared.sh
+++ b/bin/internal/shared.sh
@@ -196,2 +196,3 @@ function shared::execute() {
   export FLUTTER_ROOT="$(cd "${BIN_DIR}/.." ; pwd -P)"
+  export FLUTTER_CACHE_DIR="${FLUTTER_CACHE_DIR:-$FLUTTER_ROOT/bin/cache}"
 
@@ -205,5 +206,5 @@ function shared::execute() {
   FLUTTER_TOOLS_DIR="$FLUTTER_ROOT/packages/flutter_tools"
-  SNAPSHOT_PATH="$FLUTTER_ROOT/bin/cache/flutter_tools.snapshot"
-  STAMP_PATH="$FLUTTER_ROOT/bin/cache/flutter_tools.stamp"
+  SNAPSHOT_PATH="$FLUTTER_CACHE_DIR/flutter_tools.snapshot"
+  STAMP_PATH="$FLUTTER_CACHE_DIR/flutter_tools.stamp"
   SCRIPT_PATH="$FLUTTER_TOOLS_DIR/bin/flutter_tools.dart"
-  DART_SDK_PATH="$FLUTTER_ROOT/bin/cache/dart-sdk"
+  DART_SDK_PATH="$FLUTTER_CACHE_DIR/dart-sdk"
diff --git a/packages/flutter_tools/lib/src/cache.dart b/packages/flutter_tools/lib/src/cache.dart
--- a/packages/flutter_tools/lib/src/cache.dart
+++ b/packages/flutter_tools/lib/src/cache.dart
@@ -36,4 +36,6 @@
 const kFlutterRootEnvironmentVariableName =
     'FLUTTER_ROOT'; // should point to //flutter/ (root of flutter/flutter repo)
+const kFlutterCacheEnvironmentVariableName =
+    'FLUTTER_CACHE_DIR'; // writable cache, defaults to //flutter/bin/cache/
 const kFlutterEngineEnvironmentVariableName =
     'FLUTTER_ENGINE'; // should point to //engine/src/ (root of flutter/engine repo)
@@ -381,3 +383,1 @@
-    final File lockFile = _fileSystem.file(
-      _fileSystem.path.join(flutterRoot!, 'bin', 'cache', 'lockfile'),
-    );
+    final File lockFile = getRoot().childFile('lockfile');
@@ -581,5 +581,12 @@
   Directory getRoot() {
-    return _fileSystem.directory(
-      _fileSystem.path.join(_rootOverride?.path ?? flutterRoot!, 'bin', 'cache'),
-    );
+    if (_rootOverride != null) {
+      return _fileSystem.directory(
+        _fileSystem.path.join(_rootOverride.path, 'bin', 'cache'),
+      );
+    }
+    final String? cacheOverride = _platform.environment[kFlutterCacheEnvironmentVariableName];
+    if (cacheOverride != null && cacheOverride.isNotEmpty) {
+      return _fileSystem.directory(cacheOverride);
+    }
+    return _fileSystem.directory(_fileSystem.path.join(flutterRoot!, 'bin', 'cache'));
   }
@@ -646,8 +653,1 @@
-    final File realmFile = _fileSystem.file(
-      _fileSystem.path.join(
-        _rootOverride?.path ?? flutterRoot!,
-        'bin',
-        'cache',
-        '$artifactName.realm',
-      ),
-    );
+    final File realmFile = getRoot().childFile('$artifactName.realm');
diff --git a/packages/flutter_tools/lib/src/dart/pub.dart b/packages/flutter_tools/lib/src/dart/pub.dart
--- a/packages/flutter_tools/lib/src/dart/pub.dart
+++ b/packages/flutter_tools/lib/src/dart/pub.dart
@@ -570,9 +570,10 @@
   List<String> _computePubCommand() {
     // TODO(zanderso): refactor to use artifacts.
+    final String cacheRoot =
+        _platform.environment[kFlutterCacheEnvironmentVariableName] ??
+        _fileSystem.path.join(Cache.flutterRoot!, 'bin', 'cache');
     final String sdkPath = _fileSystem.path.joinAll(<String>[
-      Cache.flutterRoot!,
-      'bin',
-      'cache',
+      cacheRoot,
       'dart-sdk',
       'bin',
       'dart',
diff --git a/packages/flutter_tools/lib/src/flutter_cache.dart b/packages/flutter_tools/lib/src/flutter_cache.dart
--- a/packages/flutter_tools/lib/src/flutter_cache.dart
+++ b/packages/flutter_tools/lib/src/flutter_cache.dart
@@ -122,13 +122,10 @@
     OperatingSystemUtils operatingSystemUtils, {
     bool offline = false,
   }) async {
-    await _pub().get(
-      context: PubContext.pubGet,
-      project: _projectFactory.fromDirectory(
-        fileSystem.directory(fileSystem.path.join(_flutterRoot(), 'packages', 'flutter_tools')),
-      ),
-      offline: offline,
-      outputMode: PubOutputMode.failuresOnly,
+    throwToolExit(
+      'The packaged Flutter SDK is immutable and its flutter_tools dependencies '
+      'must be provided by dev-lang/flutter-bin. Reinstall the package if this '
+      'cache is incomplete.',
     );
   }
 }
diff --git a/packages/flutter_tools/lib/src/version.dart b/packages/flutter_tools/lib/src/version.dart
--- a/packages/flutter_tools/lib/src/version.dart
+++ b/packages/flutter_tools/lib/src/version.dart
@@ -175,3 +175,8 @@
   static File getVersionFile(FileSystem fs, String flutterRoot) {
+    final String? cacheOverride =
+        globals.platform.environment[kFlutterCacheEnvironmentVariableName];
+    if (cacheOverride != null && cacheOverride.isNotEmpty) {
+      return fs.file(fs.path.join(cacheOverride, 'flutter.version.json'));
+    }
     return fs.file(fs.path.join(flutterRoot, 'bin', 'cache', 'flutter.version.json'));
   }