Bylot Island, 11 067 km2, is nestled into the northeastern corner of Baffin Island at the entrance to Lancaster Sound. Its southern aspect looks across Pond Inlet and Eclipse Sound; on the west it is divided from Baffin Island by the narrow Navy Board Inlet. Bold, rugged coasts, glaciers and a high, mountainous interior have not been conducive to habitation. Its steep, rugged coastline (particularly capes Hay and Graham Moore) and a polynya centred on the entrance of Lancaster Sound offer prime habitat for seabirds. Its importance for seabirds was recognized in 1965 when the island and surrounding waters were designated as a migratory bird sanctuary. In 1999 Bylot Island became part of Sirmilik National Park.

Inuit from Baffin Island have visited seasonally and a trading station operated at Button Point on the southeastern corner for several years after 1910, but there are no settlements today. To the east the island overlooks a part of Baffin Bay, which was much frequented by European whalers in the 19th and early 20th centuries. It was officially claimed as part of Canada by Captain Joseph Elzéar Bernier in 1906. The island is named after Robert Bylot.