Dunthorpe is a census-designated place (CDP) and unincorporated suburb of Portland, Oregon, United States. As of the 2020 census, it had a population of 1,704. It is located just south of the Portland city limits and north of the Multnomah County line on the west side of the Willamette River. Lewis & Clark College, Tryon Creek State Natural Area, and Lake Oswego are nearby.