Manatee County is a county in the U.S. state of Florida. As of the 2020 U.S. Census, the population was 399,710. Manatee County is part of the North Port-Bradenton-Sarasota, Florida Metropolitan Statistical Area. Its county seat and largest city is Bradenton. The county was created in 1855 and named for the Florida manatee, Florida's official marine mammal.Wikipedia