Dewey County is a county in the western part of the U.S. state of Oklahoma. As of the 2020 census, the population was 4,484. Its county seat is Taloga. The county was created in 1891 as "County D". In an 1898 election, county voters chose the name Dewey, honoring Admiral George Dewey.

George Dewey was Admiral of the Navy, the only person in United States history to have attained that rank. He is best known for his victory at the Battle of Manila Bay during the Spanish–American War, with the loss of only a single crewman on the American side.