diff --git a/projects/plugins/jetpack/changelog/dsgcom-534-validate-site-verification-codes b/projects/plugins/jetpack/changelog/dsgcom-534-validate-site-verification-codes
new file mode 100644
index 000000000000..4d82de2c40a9
--- /dev/null
+++ b/projects/plugins/jetpack/changelog/dsgcom-534-validate-site-verification-codes
@@ -0,0 +1,4 @@
+Significance: patch
+Type: bugfix
+
+Site Verification: Reject invalid verification codes instead of reporting a successful save.
diff --git a/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php b/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
index 1b1b96fa48d4..1f61f86facee 100644
--- a/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
+++ b/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
@@ -1235,6 +1235,21 @@ function ( &$value ) {
 				case 'verification_services_codes':
 					$verification_codes = jetpack_verification_validate( $value );
 
+					foreach ( $value as $service_key => $raw_code ) {
+						if ( '' === $raw_code || null === $raw_code ) {
+							continue;
+						}
+
+						$validated_code = $verification_codes[ $service_key ] ?? '';
+						if ( '' === $validated_code ) {
+							return new WP_Error(
+								'invalid_input',
+								__( 'Invalid site verification code. Enter only the content value from the meta tag.', 'jetpack' ),
+								400
+							);
+						}
+					}
+
 					if ( update_option( 'verification_services_codes', $verification_codes ) ) {
 						$updated[ $key ] = $verification_codes;
 					}
diff --git a/projects/plugins/jetpack/modules/verification-tools/verification-tools-utils.php b/projects/plugins/jetpack/modules/verification-tools/verification-tools-utils.php
index 1f916e96a55e..268bcafe284e 100644
--- a/projects/plugins/jetpack/modules/verification-tools/verification-tools-utils.php
+++ b/projects/plugins/jetpack/modules/verification-tools/verification-tools-utils.php
@@ -13,17 +13,25 @@
 	 * @param array $verification_services_codes - array of verification codes.
 	 */
 	function jetpack_verification_validate( $verification_services_codes ) {
+		$code_pattern = '/^[a-z0-9_-]+$/i';
+
 		foreach ( $verification_services_codes as $key => $code ) {
+			$code = is_scalar( $code ) ? (string) $code : '';
+
 			// Parse html meta tag if it does not look like a valid code.
-			if ( ! preg_match( '/^[a-z0-9_-]+$/i', $code ) ) {
+			if ( ! preg_match( $code_pattern, $code ) ) {
 				$code = jetpack_verification_get_code( $code );
 			}
 
-			$code = esc_attr( trim( $code ) );
+			$code = esc_attr( trim( (string) $code ) );
 
 			// limit length to 100 chars.
 			$code = substr( $code, 0, 100 );
 
+			if ( '' !== $code && ! preg_match( $code_pattern, $code ) ) {
+				$code = '';
+			}
+
 			/**
 			 * Fire after each Verification code was validated.
 			 *
diff --git a/projects/plugins/jetpack/tests/php/json-api/WPCOM_JSON_API_Site_Settings_V1_4_Endpoint_Test.php b/projects/plugins/jetpack/tests/php/json-api/WPCOM_JSON_API_Site_Settings_V1_4_Endpoint_Test.php
index 1e67cc412998..84bd995bb700 100644
--- a/projects/plugins/jetpack/tests/php/json-api/WPCOM_JSON_API_Site_Settings_V1_4_Endpoint_Test.php
+++ b/projects/plugins/jetpack/tests/php/json-api/WPCOM_JSON_API_Site_Settings_V1_4_Endpoint_Test.php
@@ -181,6 +181,44 @@ public function test_post_settings_sets_key_values( $setting_name, $setting_valu
 		$this->assertSame( $expected_value, $updated[ $setting_name ] );
 	}
 
+	/**
+	 * Invalid site verification codes return an actionable client error and are not saved.
+	 */
+	public function test_post_rejects_invalid_site_verification_code() {
+		$setting = wp_json_encode(
+			array( 'verification_services_codes' => array( 'bing' => 'not.a.valid.token' ) ),
+			JSON_UNESCAPED_SLASHES
+		);
+
+		$response = $this->make_post_request( $setting );
+
+		$this->assertWPError( $response );
+		$this->assertSame( 'invalid_input', $response->get_error_code() );
+		$this->assertSame( 400, $response->get_error_data() );
+		$this->assertFalse( get_option( 'verification_services_codes' ) );
+	}
+
+	/**
+	 * A valid site verification meta tag is reduced to its content value and saved.
+	 */
+	public function test_post_saves_site_verification_code_from_meta_tag() {
+		$setting = wp_json_encode(
+			array(
+				'verification_services_codes' => array(
+					'bing' => '<meta name="msvalidate.01" content="12C1203B5086AECE94EB3A3D9830B2E" />',
+				),
+			),
+			JSON_UNESCAPED_SLASHES
+		);
+
+		$response = $this->make_post_request( $setting );
+
+		$this->assertSame(
+			array( 'bing' => '12C1203B5086AECE94EB3A3D9830B2E' ),
+			$response['updated']['verification_services_codes']
+		);
+	}
+
 	/**
 	 * The free tier description is capped to 500 characters to match the
 	 * paid-tier description field.
diff --git a/projects/plugins/jetpack/tests/php/modules/verification-tools/Jetpack_Verification_Tools_Utils_Test.php b/projects/plugins/jetpack/tests/php/modules/verification-tools/Jetpack_Verification_Tools_Utils_Test.php
index 0327e019dc08..7dd41ea8e533 100644
--- a/projects/plugins/jetpack/tests/php/modules/verification-tools/Jetpack_Verification_Tools_Utils_Test.php
+++ b/projects/plugins/jetpack/tests/php/modules/verification-tools/Jetpack_Verification_Tools_Utils_Test.php
@@ -1,6 +1,7 @@
 <?php
 
 use PHPUnit\Framework\Attributes\CoversFunction;
+use PHPUnit\Framework\Attributes\DataProvider;
 require __DIR__ . '/../../../../modules/verification-tools/verification-tools-utils.php';
 
 /**
@@ -45,4 +46,66 @@ public function test_jetpack_verification_validate_google_code_in_meta_single_qu
 			'google-style meta tag with single quotes should be accepeted'
 		);
 	}
+
+	/**
+	 * Verification codes with valid characters are accepted for every service.
+	 *
+	 * @dataProvider valid_verification_code_provider
+	 *
+	 * @param string $service Verification service key.
+	 * @param string $code    Verification code.
+	 */
+	#[DataProvider( 'valid_verification_code_provider' )]
+	public function test_valid_code_is_accepted_for_every_service( $service, $code ) {
+		$this->assertSame(
+			array( $service => $code ),
+			jetpack_verification_validate( array( $service => $code ) )
+		);
+	}
+
+	/**
+	 * Verification codes with invalid characters are rejected for every service.
+	 *
+	 * @dataProvider invalid_verification_code_provider
+	 *
+	 * @param string $service Verification service key.
+	 * @param string $code    Verification code.
+	 */
+	#[DataProvider( 'invalid_verification_code_provider' )]
+	public function test_invalid_code_is_rejected_for_every_service( $service, $code ) {
+		$this->assertSame(
+			array( $service => '' ),
+			jetpack_verification_validate( array( $service => $code ) )
+		);
+	}
+
+	/**
+	 * Provide valid verification codes.
+	 *
+	 * @return array<string, array{string, string}> Test cases.
+	 */
+	public static function valid_verification_code_provider() {
+		return array(
+			'google'    => array( 'google', 'verification_Code-123' ),
+			'bing'      => array( 'bing', 'verification_Code-123' ),
+			'pinterest' => array( 'pinterest', 'verification_Code-123' ),
+			'yandex'    => array( 'yandex', 'verification_Code-123' ),
+			'facebook'  => array( 'facebook', 'verification_Code-123' ),
+		);
+	}
+
+	/**
+	 * Provide invalid verification codes.
+	 *
+	 * @return array<string, array{string, string}> Test cases.
+	 */
+	public static function invalid_verification_code_provider() {
+		return array(
+			'google'    => array( 'google', 'invalid.code' ),
+			'bing'      => array( 'bing', 'invalid.code' ),
+			'pinterest' => array( 'pinterest', 'invalid.code' ),
+			'yandex'    => array( 'yandex', 'invalid.code' ),
+			'facebook'  => array( 'facebook', 'invalid.code' ),
+		);
+	}
 }