There are a total of 77 counties in the state of Oklahoma. Among them, Beaver County is the oldest one (established in 1890) while Cotton County is the youngest (established in 1912). With population of 718,633, Oklahoma County is the most populated. The biggest county by land area is Osage County (5,830 km2) and the smallest is Marshall County (961 km2). Below please see all Oklahoma counties which are listed in alphabetical order.
- Adair County, OK
- Alfalfa County, OK
- Atoka County, OK
- Beaver County, OK
- Beckham County, OK
- Blaine County, OK
- Bryan County, OK
- Caddo County, OK
- Canadian County, OK
- Carter County, OK
- Cherokee County, OK
- Choctaw County, OK
- Cimarron County, OK
- Cleveland County, OK
- Coal County, OK
- Comanche County, OK
- Cotton County, OK
- Craig County, OK
- Creek County, OK
- Custer County, OK
- Delaware County, OK
- Dewey County, OK
- Ellis County, OK
- Garfield County, OK
- Garvin County, OK
- Grady County, OK
- Grant County, OK
- Greer County, OK
- Harmon County, OK
- Harper County, OK
- Haskell County, OK
- Hughes County, OK
- Jackson County, OK
- Jefferson County, OK
- Johnston County, OK
- Kay County, OK
- Kingfisher County, OK
- Kiowa County, OK
- Latimer County, OK
- Le Flore County, OK
- Lincoln County, OK
- Logan County, OK
- Love County, OK
- Major County, OK
- Marshall County, OK
- Mayes County, OK
- McClain County, OK
- McCurtain County, OK
- McIntosh County, OK
- Murray County, OK
- Muskogee County, OK
- Noble County, OK
- Nowata County, OK
- Okfuskee County, OK
- Oklahoma County, OK
- Okmulgee County, OK
- Osage County, OK
- Ottawa County, OK
- Pawnee County, OK
- Payne County, OK
- Pittsburg County, OK
- Pontotoc County, OK
- Pottawatomie County, OK
- Pushmataha County, OK
- Roger Mills County, OK
- Rogers County, OK
- Seminole County, OK
- Sequoyah County, OK
- Stephens County, OK
- Texas County, OK
- Tillman County, OK
- Tulsa County, OK
- Wagoner County, OK
- Washington County, OK
- Washita County, OK
- Woods County, OK
- Woodward County, OK