The original Kearney County was created on March 6, 1873. It was ended in 1883. The land area was divided between Hamilton and Finney counties. It was recreated with its original borders in 1887. It was organized on March 27, 1888. The county is named after Philip Kearny. He was a U.S. Army officer in the Mexican–American War and a Union army general in the American Civil War. In 1889, the name was corrected to Kearny County.