Kulusuk Island is an island in the Sermersooq municipality on the southeastern shore of Greenland. It is an outlying island in the Ammassalik archipelago of islands on the coast of the North Atlantic. The island is home to Kulusuk, the fourth-largest settlement on the entire eastern coast of Greenland.
The coast of most of the island is mostly undeveloped, with the mountain walls and slopes falling directly into the ocean. In the west there are several small peninsulas and bays. The island is hilly, and unlike its immediate neighbours, not glaciated, albeit covered with ice for more than half of the year. The highest point on the island is the summit of Qalorujoorneq, at 676 m (2,217.8 ft) topping a wide mountain massif in the southeast, directly above the Kulusuk Airport.
There is one larger lake on the island, Qalorujoornep Tasia, located in a post-glacial cirque in the heart of the island directly west of the western wall of Qalorujoorneq. Its northern shore is situated just shy of the shallow saddle in the northwestern ridge of the mountain, directly above the airport.