Lake Fenton is a census-designated place in Fenton Charter Township, Genesee County in the U.S. state of Michigan. As of the 2010 census the population was 5,559, up from 4,876 at the 2000 census. The CDP includes the unincorporated communities of Bayport Park and Lakeside. The Lake Fenton Community Schools district overlaps a portion of this and adjacent areas. The school district and community are named after Lake Fenton, formerly known as Long Lake.