Sanibel is an island and city in Lee County, Florida, United States. The population was 6,382 at the 2020 census, down from 6,469 at the 2010 census. It is part of the Cape Coral-Fort Myers, Florida Metropolitan Statistical Area. The island, also known as Sanibel Island, constitutes the entire city. It is a barrier island—a collection of sand on the leeward side of the more solid coral-rock of Pine Island.

Lee County is located in southwestern Florida, United States, on the Gulf Coast. As of the 2020 census, its population was 760,822. In 2022, the population was 822,453, making it the eighth-most populous county in the state. The county seat is Fort Myers, with a population of 86,395 as of the 2020 census, and the largest city is Cape Coral, with an estimated 2020 population of 194,016.