Some of the cities, towns, and places in Umatilla County are Adams, Athena, Bingham Springs, Blakeley, Cayuse, Cold Springs, Cold Springs Junction, Echo, Ferndale, Gibbon, Gopher Flats, Havana, Helix, Hermiston, Hinkle, Holdman, Kirkpatrick, Lehman Springs, McKay, McNary, Meacham, Milton-Freewater, Mission, Myrick, Nolin, Nye, Ordnance, Pendleton, Pilot Rock, Rieth, Riverside, Riverview, Stanfield, Sunnyside, Tollgate, Tutuilla, Ukiah, Umapine, Umatilla, Weston
Umatilla County () is one of the 36 counties in the U.S. state of Oregon. As of the 2010 census, the population was 75,889. The county seat is Pendleton, but the largest city is Hermiston. The county is named for the Umatilla River.
Umatilla County is part of the Hermiston-Pendleton, OR Micropolitan Statistical Area. It is included in the eight-county definition of Eastern Oregon.