Sugarmouse Island is an unpopulated islet located close to the south-western coast of Tasmania, Australia.

Situated some 2 kilometres (1.2 mi) south of where the mouth of Port Davey meets the Southern Ocean, the 0.54-hectare (1.3-acre) islet is one of the eight islands that comprise the Mutton Bird Islands Group.

Sugarmouse Island is part of the Southwest National Park and the Tasmanian Wilderness World Heritage Site.

[1][2] The island is part of the Port Davey Islands Important Bird Area, so identified by BirdLife International because of its importance for breeding seabirds.

[3] Recorded breeding seabird species are the fairy prion (2000 pairs) and black-faced cormorant.