South Lyon is a city in southwestern Oakland County in the U.S. state of Michigan. The population was 11,327 at the 2010 census. The city is part of the South Lyon-Howell-Brighton Urban Area, which had a population of 106,139 according to the 2000 census. South Lyon is located in Oakland County's Lyon Township, near the Livingston County and Washtenaw County lines. The city is 19 miles north of Ann Arbor, 45 miles west of Detroit and 58 miles east of Lansing.