| CONGRESS | SENATOR | TERM BEGAN | TERM ENDED | COMMENTS |
|---|---|---|---|---|
| Class 2 | ||||
| 44th-47th | Henry M. Teller (R) | Nov. 15, 1876 | Apr. 17, 1882 | Resigned |
| 47th | George M. Chilcott (R) | Apr. 17, 1882 | Jan. 27, 1883 | Appointed |
| 47th | Horace A. W. Tabor (R) | Jan. 27, 1883 | Mar. 3, 1883 | |
| 48th-50th | Thomas M. Bowen (R) | Mar. 4, 1883 | Mar. 3, 1889 | |
| 51st-56th | Edward O. Wolcott (R) | Mar. 4, 1889 | Mar. 3, 1901 | |
| 57th-59th | Thomas M. Patterson (D) | Mar. 4, 1901 | Mar. 3, 1907 | |
| 60th-62nd | Simon Guggenheim (R) | Mar. 4, 1907 | Mar. 3, 1913 | |
| 63rd-65th | John F. Shafroth (D) | Mar. 4, 1913 | Mar. 3, 1919 | |
| 66th-71st | Lawrence C. Phipps (R) | Mar. 4, 1919 | Mar. 3, 1931 | |
| 72nd-74th | Edward P. Costigan (D) | Mar. 4, 1931 | Jan. 3, 1937 | |
| 75th-83rd | Edwin C. Johnson (D) | Jan. 3, 1937 | Jan. 3, 1955 | |
| 84th-92nd | Gordon L. Allott (R) | Jan. 3, 1955 | Jan. 3, 1973 | |
| 93rd-95th | Floyd K. Haskell (D) | Jan. 3, 1973 | Jan. 3, 1979 | |
| 96th-101st | William L. Armstrong (R) | Jan. 3, 1979 | Jan. 3, 1991 | |
| 102nd-104th | George Hanks (Hank) Brown (R) | Jan. 3, 1991 | Jan. 3, 1997 | |
| 105th-110th | A. Wayne Allard (R) | Jan. 3, 1997 | Jan. 3, 2009 | |
| 111th-113th | Mark Udall (D) | Jan. 3, 2009 | Jan. 3, 2015 | |
| 114th-116th | Cory Gardner (R) | Jan. 3, 2015 | Jan. 3, 2021 | |
| 117th- | John Wright Hickenlooper (D) | Jan. 3, 2021 | Present | |
| Class 3 | ||||
| 44th-45th | Jerome B. Chaffee (R) | Nov. 15, 1876 | Mar. 3, 1879 | |
| 46th-48th | Nathaniel P. Hill (R) | Mar. 4, 1879 | Mar. 3, 1885 | |
| 49th-60th | Henry M. Teller (R, SR, D) | Mar. 4, 1885 | Mar. 3, 1909 | |
| 61st | Charles J. Hughes Jr. (D) | Mar. 4, 1909 | Jan. 11, 1911 | Died |
| 62nd-66th | Charles S. Thomas (D) | Jan. 15, 19131 | Mar. 3, 1921 | |
| 67th | Samuel D. Nicholson (R) | Mar. 4, 1921 | Mar. 24, 1923 | Died |
| 67th-68th | Alva B. Adams (D) | May 17, 1923 | Nov. 30, 1924 | Appointed |
| 68th-69th | Rice W. Means (R) | Dec. 1, 1924 | Mar. 3, 1927 | |
| 70th-72nd | Charles W. Waterman (R) | Mar. 4, 1927 | Aug. 27, 1932 | Died |
| 72nd | Walter Walker (D) | Sept. 26, 1932 | Dec. 6, 1932 | Appointed |
| 72nd | Karl C. Schuyler (R) | Dec. 7, 1932 | Mar. 3, 1933 | |
| 73rd-77th | Alva B. Adams (D) | Mar. 4, 1933 | Dec. 1, 1941 | Died |
| 77th-84th | Eugene D. Millikin (R) | Dec. 20, 1941 | Jan. 3, 1957 | Appointed, then elected |
| 85th-87th | John A. Carroll (D) | Jan. 3, 1957 | Jan. 3, 1963 | |
| 88th-93rd | Peter H. Dominick (R) | Jan. 3, 1963 | Jan. 3, 1975 | |
| 94th-99th | Gary W. Hart (D) | Jan. 3, 1975 | Jan. 3, 1987 | |
| 100th-102nd | Timothy E. Wirth (D) | Jan. 3, 1987 | Jan. 3, 1993 | |
| 103rd-108th | Ben Nighthorse Campbell (D, R) | Jan. 3, 1993 | Jan. 3, 2005 | |
| 109th-111th | Kenneth L. Salazar (D) | Jan. 3, 2005 | Jan. 20, 2009 | Resigned |
| 111th- | Michael F. Bennet (D) | Jan. 21, 2009 | Present | Appointed, then elected |
1. Vacancy from Jan. 11, 1911, to Jan. 14, 1913, because of failure of legislature to elect.
