Born in Yankton, South Dakota, Gurney attended the public schools. During World War I, he served as a sergeant in Company A, Thirty-Fourth Engineers, United States Army, with service overseas from 1918 to 1919. He also engaged in the seed and nursery business from 1914 to 1926, and was the operator of a radio station at Yankton from 1926 to 1932. He then moved to Sioux Falls, South Dakota and engaged in the wholesale gasoline and oil business from 1932 to 1936.

In 1936, Gurney ran unsuccessfully for election to the United States Senate, but he was elected as a Republican in 1938. He was reelected in 1944 and served in all from January 3, 1939 to January 3, 1951. He was chairman of the U.S. Senate Committee on Armed Services. He did not run for a third term in the Senate because he was defeated in the Republican primary by Francis Case.

After his time in Congress, Gurney was appointed a member of the Civil Aeronautics Board in 1951, became chairman in 1954, and served until 1964. He retired to Yankton, where he died and was buried in Yankton Cemetery.