The elevation of Keller is 1,499 feet above sea level. The CDP makes up 9.5 square miles, all of it land.
The town is located in the valley of the Sanpoil River, and was founded in 1898 by John C. Keller, a local businessman. The town was located in the area now known as the "San Poil Bay" (or "Old Keller" to the locals); at its height the town had an estimated population of 3,500 and even featured a minor league baseball team and a red light district. The town was moved several times beginning in 1941 due to backwatering from the Grand Coulee Dam which flooded its previous locations, and is now located 18 miles north of the Columbia River. The series of moves seriously reduced its population over time.
The town is encompassed by the Colville Indian Reservation, which has an estimated population of roughly 1,200 people mostly of Native American descent and primarily members of the Sanpoil tribe, one of the Twelve Tribes that make up the Colville Confederated Tribes and one of the few Indian Nations that was never relocated by order of the U.S. government.