A heat sink assembly includes a base, a fin group located above a top of the base, a mounting bracket, and a fan mounted on a lateral side of the mounting bracket. The mounting bracket is integrally formed by a metal sheet. The mounting bracket includes a pedestal is located at a top of the base and connects with the base, and two sidewalls extending upwardly from opposite ends of the pedestal and sandwiching the fin group therebetween. The fan is mounted on a lateral side of the sidewalls of the mounting bracket. The pedestal integrally forms four mounting arms. Four fasteners extend through the mounting arms for securing the heat sink assembly to a printed circuit board.