- Comanche County: Named after the Comanche people, a Native American tribe indigenous to the Southern Plains of the United States.
- Custer County: Named after George Armstrong Custer, a U.S. Army officer and cavalry commander who fought in the American Civil War and the Indian Wars.
- Garfield County: Named after James A. Garfield, the 20th President of the United States.
- Grant County: Named after Ulysses S. Grant, the 18th President of the United States.
- Harmon County: Named after Judson Harmon, the 45th Governor of Ohio and U.S. Attorney General under President Grover Cleveland.
- Jackson County: Named after Andrew Jackson, the 7th President of the United States.
- Jefferson County: Named after Thomas Jefferson, the 3rd President of the United States.
- Kay County: Named after John Kay, a prominent early settler of the area and a member of the Cherokee Nation.
- Lincoln County: Named after Abraham Lincoln, the 16th President of the United States.
- Logan County: Named after John A. Logan, a U.S. Army general during the American Civil War and a U.S. Senator from Illinois.
- Love County: Named after Overton Love, a prominent early settler of the area and a member of the Chickasaw Nation.
- Marshall County: Named after John Marshall, the 4th Chief Justice of the United States.
- Mayes County: Named after Joel Mayes, a prominent early settler of the area and a member of the Cherokee Nation.
- McCurtain County: Named after William McCurtain, a prominent early settler of the area and a member of the Choctaw Nation.
- McIntosh County: Named after William McIntosh, a prominent early settler of the area and a member of the Creek Nation.
- Murray County: Named after William H. Murray, the first Governor of Oklahoma.
- Noble County: Named after John Willock Noble, the 20th Secretary of the Interior under President Benjamin Harrison.
- Osage County: Named after the Osage people, a Native American tribe indigenous to the Great Plains region of the United States.
- Ottawa County: Named after the Ottawa people, a Native American tribe indigenous to the Great Lakes region of the United States.
- Payne County: Named after David L. Payne, a prominent early settler of the area and a member of the Cherokee Nation.
- Rogers County: Named after Will Rogers, a famous American humorist, actor, and cowboy philosopher.
- Sequoyah County: Named after Sequoyah, a prominent Cherokee leader who developed the Cherokee syllabary, a writing system for the Cherokee language.
- Washita County: Named after the Washita people, a Native American tribe indigenous to the Southern Plains of the United States.
