diff --git a/changelog/add-3943-send-blog-theme-to-sift b/changelog/add-3943-send-blog-theme-to-sift
new file mode 100644
index 00000000000..7f67989d63f
--- /dev/null
+++ b/changelog/add-3943-send-blog-theme-to-sift
@@ -0,0 +1,4 @@
+Significance: minor
+Type: add
+
+Add the active theme name of the blog to the compatibility service
diff --git a/includes/class-compatibility-service.php b/includes/class-compatibility-service.php
index 444b3383cb1..d258b0f740e 100644
--- a/includes/class-compatibility-service.php
+++ b/includes/class-compatibility-service.php
@@ -39,6 +39,7 @@ public function __construct( WC_Payments_API_Client $payments_api_client ) {
 	 */
 	public function init_hooks() {
 		add_action( 'woocommerce_payments_account_refreshed', [ $this, 'update_compatibility_data' ] );
+		add_action( 'after_switch_theme', [ $this, 'update_compatibility_data' ] );
 	}
 
 	/**
@@ -52,6 +53,7 @@ public function update_compatibility_data() {
 				[
 					'woopayments_version' => WCPAY_VERSION_NUMBER,
 					'woocommerce_version' => WC_VERSION,
+					'blog_theme'          => get_stylesheet(),
 				]
 			);
 		} catch ( API_Exception $e ) { // phpcs:ignore Generic.CodeAnalysis.EmptyStatement.DetectedCatch
diff --git a/tests/unit/test-class-compatibility-service.php b/tests/unit/test-class-compatibility-service.php
index 70e86b5d2dc..0e5cfa53b0a 100644
--- a/tests/unit/test-class-compatibility-service.php
+++ b/tests/unit/test-class-compatibility-service.php
@@ -40,13 +40,24 @@ public function set_up() {
 	public function test_registers_woocommerce_filters_properly() {
 		$priority = has_filter( 'woocommerce_payments_account_refreshed', [ $this->compatibility_service, 'update_compatibility_data' ] );
 		$this->assertEquals( 10, $priority );
+		$priority = has_action( 'after_switch_theme', [ $this->compatibility_service, 'update_compatibility_data' ] );
+		$this->assertEquals( 10, $priority );
 	}
 
 	public function test_update_compatibility_data() {
+		$stylesheet = 'my_theme_name';
+		add_filter(
+			'stylesheet',
+			function( $theme ) use ( $stylesheet ) {
+				return $stylesheet;
+			}
+		);
+
 		// Arrange: Create the expected value to be passed to update_compatibility_data.
 		$expected = [
 			'woopayments_version' => WCPAY_VERSION_NUMBER,
 			'woocommerce_version' => WC_VERSION,
+			'blog_theme'          => $stylesheet,
 		];
 
 		// Arrange/Assert: Set the expectations for update_compatibility_data.