| Mattaangassut | |
| Map: | Greenland |
| Archipelago: | Upernavik Archipelago |
| Location: | Greenland |
| Coordinates: | 73.5556°N -56.7333°W |
| Country: | Greenland |
| Country Admin Divisions Title: | Municipality |
| Country Admin Divisions: | Avannaata |
Mattaangassut Island (old spelling: Mátângassut) is an uninhabited island in Avannaata municipality in northwestern Greenland.
Mattaangassut Island is located in Tasiusaq Bay, in the north-central part of Upernavik Archipelago. It is separated from Nutaarmiut Island in the southeast by a narrow Ikerasakassak strait, and from Qallunaat Island in the east by the waterways of Tasiusaq Bay.[1]