diff --git a/types/prettier/index.d.ts b/types/prettier/index.d.ts
index 48c89a5c57..07cf09fbba 100644
--- a/types/prettier/index.d.ts
+++ b/types/prettier/index.d.ts
@@ -102,6 +102,10 @@ export interface ResolveConfigOptions {
      * If set to `false`, all caching will be bypassed.
      */
     useCache?: boolean;
+    /**
+     * If set to `true`, result will be returned directly.
+     */
+    sync?: boolean;
 }
 
 /**
@@ -114,7 +118,9 @@ export interface ResolveConfigOptions {
  *
  * The promise will be rejected if there was an error parsing the configuration file.
  */
-export function resolveConfig(filePath?: string, options?: ResolveConfigOptions): Promise<null | Options>;
+export function resolveConfig(filePath: string | undefined, options: ResolveConfigOptions & { sync: true }): null | Options;
+export function resolveConfig(filePath?: string, options?: ResolveConfigOptions & { sync?: false }): Promise<null | Options>;
+export function resolveConfig(filePath?: string, options?: ResolveConfigOptions): null | Options | Promise<null | Options>;
 
 /**
  * As you repeatedly call `resolveConfig`, the file system structure will be cached for performance. This function will clear the cache.
diff --git a/types/prettier/prettier-tests.ts b/types/prettier/prettier-tests.ts
index a51e8902c4..e88ebe4770 100644
--- a/types/prettier/prettier-tests.ts
+++ b/types/prettier/prettier-tests.ts
@@ -24,4 +24,30 @@ prettier.resolveConfig('path/to/somewhere').then(options => {
     }
 });
 
+prettier.resolveConfig('path/to/somewhere', undefined).then(options => {
+    if (options !== null) {
+        const formatted = prettier.format('hello world', options);
+    }
+});
+
+prettier.resolveConfig('path/to/somewhere', {}).then(options => {
+    if (options !== null) {
+        const formatted = prettier.format('hello world', options);
+    }
+});
+
+prettier.resolveConfig('path/to/somewhere', { sync: false }).then(options => {
+    if (options !== null) {
+        const formatted = prettier.format('hello world', options);
+    }
+});
+
+// $ExpectType Options | Promise<Options | null> | null
+prettier.resolveConfig('path/to/somewhere', { sync: true as boolean });
+
+const options = prettier.resolveConfig('path/to/somewhere', { sync: true });
+if (options !== null) {
+    const formatted = prettier.format('hello world', options);
+}
+
 prettier.clearConfigCache();