Oneco, pronounced oh-nee-cō, is an unincorporated community in Manatee County, Florida, United States. It is a suburb of Bradenton, located just southeast of the city. The community is part of the Bradenton–Sarasota–Venice Metropolitan Statistical Area. In the 1920 Census it was enumerated as Precinct 6. The community reported as a Census-designated place by the U.S.