|State||Kingdom of Denmark|
|Postal code||3962 Upernavik|
Tasiusaq (old spelling: Tasiussaq) is an island settlement in the Qaasuitsup municipality in northwestern Greenland. It had 248 inhabitants in 2010. In Kalaallisut, the name means "Bay with a Small Outlet".
Tasiusaq is located within Upernavik Archipelago, a vast archipelago of small islands on the coast of northeastern Baffin Bay. The archipelago extends from the northwestern coast of Sigguup Nunaa peninsula in the south at approximately  to the southern end of Melville Bay (Greenlandic: Qimusseriarsuaq) in the north at approximately .
Tasiusaq is one of the few settlements in the Qaasuitsup municipality exhibiting significant growth patterns over the course of the last two decades, increasing by nearly half relative to the 1990 levels and by over 7 percent relative to the 2000 levels.