O'Leary Island is an uninhabited island in Qikiqtaaluk Region, Nunavut, Canada. Located in Hudson Bay, it is a member of the Belcher Islands group. It lies at the southeast end of Omarolluk Sound between Ridge Passage to the north and Narrow Passage to its south; Broomfield Island runs parallel to its east side. Other islands in the immediate vicinity include:

• Broomfield Island
• Innetalling Island
• Snape Island
• Walton Island