| Shoup, George L. (Republican) |
1890 to December 1890 |
| Willey, N.B. (Republican) |
December 1890 to January 1893 |
| McConnell, William J. (Republican) |
January 1893 to January 4, 1897 |
| Steunenberg, Frank (P-D) |
January 4, 1897 to January 7, 1901 |
| Hunt, Frank W. (Democrat) |
January 7, 1901 to January 5, 1903 |
| Morrison, John T. (Republican) |
January 5, 1903 to January 2, 1905 |
| Gooding, Frank R. (Republican) |
January 3, 1905 to January 4, 1909 |
| Brady, James H. (Republican) |
January 4, 1909 to January 2, 1911 |
| Hawley, James H. (Democrat) |
January 2, 1911 to January 6, 1913 |
| Haines, John M. (Republican) |
January 6, 1913 to January 4, 1915 |
| Alexander, Moses (Democrat) |
January 4, 1915 to January 6, 1919 |
| Davis, D.W. (Republican) |
January 6, 1919 to January 1, 1923 |
| Moore, Charles C. (Republican) |
January 3, 1923 to January 3, 1927 |
| Baldridge, H.C. (Republican) |
January 3, 1927 to January 5, 1931 |
| Ross, C. Ben (Democrat) |
January 5, 1931 to January 4, 1937 |
| Clark, Barzilla W. (Democrat) |
January 4, 1937 to January 2, 1939 |
| Bottolfsen, C.A. (Republican) |
January 1, 1939 to January 5, 1941 |
| Clark, Chase A. (Democrat) |
January 6, 1941 to January 4, 1943 |
| Bottolfsen, C.A. (Republican) |
January 4, 1943 to January 1, 1945 |
| Gossett, Chas. C. (Democrat) |
January 1, 1945 to November 17, 1945 |
| Williams, Arnold (Democrat) |
November, 17 1945 to January 6, 1947 |
| Robins, Dr. C.A. (Republican) |
January 6, 1947 to January 1, 1951 |
| Jordan, Len B. (Republican) |
January 1, 1951 to January 3, 1955 |
| Smylie, Robert E. (Republican) |
January 3,1955 to January 2, 1967 |
| Samuelson, Don (Republican) |
January 2, 1967 to January 4, 1971 |
| Andrus, Cecil D. (Democrat) |
January 4, 1971 to January 24, 1977 |
| Evans, John V. (Democrat) |
January 24, 1977 to January 5, 1987 |
| Andrus, Cecil D. (Democrat) |
January 5, 1987 to January 1, 1995 |
| Batt, Phillip E. (Republican) |
January 2, 1995 to January 3, 1999 |
| Kempthorne, Dirk (Republican) |
January 4, 1999 to May 25, 2006 |
| Risch, James E. (Republican) |
May 26, 2006 to January 1, 2007 |
| Otter, C.L. “Butch” (Republican) |
January 1, 2007 to January 7, 2019 |
| Little, Brad (Republican) |
January 7, 2019 to present |