Waverly is a city in Bremer County, Iowa, United States. The population was 10,394 at the time of the 2020 census. It is the county seat of Br…Waverly is a city in Bremer County, Iowa, United States. The population was 10,394 at the time of the 2020 census. It is the county seat of Bremer County and is part of the Waterloo–Cedar Falls Metropolitan Statistical Area.