Walker is a city in Linn County, Iowa. The population was 688 at the 2020 census. It is part of the Cedar Rapids, Iowa metropolitan area.

Linn County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 230,299, making it the second-most populous county in Iowa. The county seat is Cedar Rapids. Linn County is named in honor of Senator Lewis F. Linn of Missouri. Linn County is included in the Cedar Rapids, IA Metropolitan Statistical Area.