A heat dissipating semiconductor package and a fabrication method thereof are provided. A semiconductor chip is mounted on a chip carrier. A heat sink is mounted on the chip, and includes an insulating core layer, a thin metallic layer formed on each of an upper surface and a lower surface of the insulating core layer and a thermal via hole formed in the insulating core layer. A molding process is performed to encapsulate the chip and the heat sink with an encapsulant to form a package unit. A singulation process is performed to peripherally cut the package unit. A part of the encapsulant above the thin metallic layer on the upper surface of the heat sink is removed, such that the thin metallic layer on the upper surface of the heat sink is exposed, and heat generated by the chip can be dissipated through the heat sink.