Crab Island may refer to:
United States:
- Crab Island (Florida), a shoal near Destin, Florida
- Crab Island (Lake Champlain), New York
- Crab Island (Washington), one of the San Juan Islands
- Crab Island (West Virginia), on the Ohio River
- A former British name for Vieques, Puerto Rico
Elsewhere:
- Crab Island (Queensland), Australia, in the western Torres Strait
- Crab Island, Guyana, at the mouth of the Berbice River
- Crab Island, Malaysia (Pulau Ketam)