It has 1,936.16 km2 (747.56 sq mi) of land area, making it the 15th largest island in the United States.

The entire island is part of Tongass National Forest.

The island's name comes from Kuiu Kwaan people of the Tlingit who lived here post glaciation.

[1] After a smallpox epidemic that nearly wiped out the entire village, the survivors moved to the neighboring Tlingit communities of Kake and Klawock.

The Cape Decision Light is located on Kuiu Island.