Long Island is an island of New York State. It may also be:
- Long Island (Antarctica), a small island off the Antarctic Peninsula
- Long Island, Antigua, a small island off the coast of Antigua
- Long Island (New South Wales), an island in the Hawkesbury River north of Sydney, New South Wales
- Long Island (Whitsunday Islands), island in the Whitsunday Group, Queensland
- Long Island (Tasmania), island in eastern Bass Strait
- Long Island, Hogan Group (Tasmania), island in northern Bass Strait
- Long Island (British Columbia), on Harrison Lake
- Long Island (Frobisher Bay, Nunavut), off the coast of Baffin Island
- Long Island (Gull Lake), near Gravenhurst, Ontario
- Long Island (Hudson Bay, Nunavut), off the coast of Quebec
- Long Island (Nova Scotia)
- Dugi otok (literally meaning Long Island), an island near Zadar, Croatia
- Bleaker Island, also called Long Island
- Cheung Chau (literally meaning Long Island), a small island southwest of Hong Kong
- Long Island, Namibia, two islands (North and South) of the Penguin Islands
- Long Island, Marlborough, an island in the Marlborough Sounds
- Long Island, Southland, an island in Fiordland
- Long Island (Papua New Guinea)
- Long Island, Seychelles, one of the inner granitic islands of the Seychelles
- Long Island, Sri Lanka, another name for Delft Island or Nedun Theevu, Sri Lanka
- Inchfad (meaning long island), Stirling
- Long Island (Dorset), Poole Harbour, Dorset, England
- Long Island (Hampshire), England
- Outer Hebrides in Scotland are sometimes referred to as "The Long Island" (An t-Eilean Fada)
- Long Island, County Down, a townland in County Down, Northern Ireland
- Long Island, County Fermanagh, a townland in County Fermanagh, Northern Ireland
- Long Island AVA, New York wine region
- Long Island (Alaska), an island in the Alexander Archipelago of southeastern Alaska
- Long Island (Connecticut), a small island near Stratford in the Housatonic River
- Long Island, Florida, a barrier island in Florida
- Long Island, Kansas, a city in Phillips County
- Long Island, Maine, a town on an island of the same name in Cumberland County
- Long Island (Cecil County, Maryland) an island in Maryland
- Long Island (Maryland) an island in Maryland
- Long Island (Massachusetts), the longest island in Boston Harbor
- Long Island (Montana), an island in Lake Bowdoin
- Long Island (Tennessee), an island on the Holston River
- Long Island, Virginia, a town in Campbell County, Virginia
- Long Island (Washington), one of the San Juan Islands
- Long Island (Wisconsin), one of the Apostle Islands in Lake Superior
- Long Island City an area of Queens in New York
- USS Long Island, the name of two United States Navy ships
- Lon Gisland EP by Beirut