Nunatakassaup Sermia (old spelling: Nunatakavsaup Sermia) is a tidewater glacier in the Qaasuitsup municipality on the northwestern shore of Greenland. It drains the Greenland ice sheet southwestwards into Tasiusaq Bay. The glacier front is located to the southeast of the Nunatarsuaq nunatak, and to the north of the Qassersuaq Peninsula.