Oakdale is a city in Washington County, Minnesota, United States. It is a suburb of Saint Paul and is on the eastern side of the Twin Cities Met…Oakdale is a city in Washington County, Minnesota, United States. It is a suburb of Saint Paul and is on the eastern side of the Twin Cities Metropolitan area. The population was 28,303 at the 2020 census. Oakdale is the 36th largest city in Minnesota by population.