Bagley is a town in Guthrie County, Iowa, United States. The population was 233 in the 2020 census, a decline from 354 in 2000 census. It is …Bagley is a town in Guthrie County, Iowa, United States. The population was 233 in the 2020 census, a decline from 354 in 2000 census. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area.