Walla Walla is a city in and the county seat of Walla Walla County, Washington, United States. It had a population of 34,060 at the 2020 …Walla Walla is a city in and the county seat of Walla Walla County, Washington, United States. It had a population of 34,060 at the 2020 census, estimated to have decreased to 33,339 as of 2023. The combined population of the city and its two suburbs, the town of College Place and unincorporated Walla Walla East, is about 45,000.