A heat sink assembly includes a heat sink and a clip for mounting the heat sink to an electronic component of a printed circuit board. The heat sink includes a base and a plurality of fins extending from the base. The clip includes a pressing member and a pair of elongated arms formed on opposite ends of the pressing member. The pressing member has a lower portion protruding toward the base of the heat sink. A middle one of the fins extends upwardly through the pressing member in a manner such that the lower portion of the pressing member resiliently abuts against the heat sink. The two arms are located on opposite lateral sides of the heat sink and bent downwardly to engage with the printed circuit board so that the pressing member exerts a force on the heat sink toward the electronic component.