Lake Butler is a census-designated place and unincorporated area, completely surrounding the town of Windermere, in Orange County, Florida, United States. The population was 15,400 at the 2010 census, up from 7,062 at the 2000 census. It is part of the Orlando–Kissimmee–Sanford, Florida Metropolitan Statistical Area. The Lake Butler CDP contains the communities of Isleworth and Summerport Beach.