| CONGRESS | SENATOR | TERM BEGAN | TERM ENDED | COMMENTS |
|---|---|---|---|---|
| Class 1 | ||||
| 1st-2nd | Charles (of Carrollton) Carroll (Pro-Admin) | Mar. 4, 1789 | Nov. 30, 1792 | Resigned |
| 2nd-4th | Richard Potts (Pro-Admin) | Jan. 10, 1793 | Oct. 24, 1796 | Resigned |
| 4th-7th | John E. Howard (F) | Nov. 21, 1796 | Mar. 3, 1803 | |
| 8th-13th | Samuel Smith (DR, CRR, J)1 | Mar. 4, 1803 | Mar. 3, 1815 | |
| 14th | Robert G. Harper (F)2 | Jan. 29, 1816 | Dec. 6, 1816 | Resigned |
| 14th-16th | Alexander Contee Hanson (F) | Dec. 20, 1816 | Apr. 23, 1819 | Died |
| 16th-17th | William Pinkney (DR) | Dec. 21, 1819 | Feb. 25, 1822 | Died |
| 17th-23rd | Samuel Smith (DR, CRR, J) | Dec. 16, 1822 | Mar. 3, 1833 | |
| 23rd-25th | Joseph Kent (AJ) | Mar. 4, 1833 | Nov. 24, 1837 | Died |
| 25th-28th | William D. Merrick (W) | Jan. 4, 1838 | Mar. 3, 1845 | |
| 29th-31st | Reverdy Johnson (W, U, D) | Mar. 4, 1845 | Mar. 7, 1849 | Resigned |
| 31st | David Stewart (W) | Dec. 6, 1849 | Jan. 12, 1850 | Appointed |
| 31st-34th | Thomas G. Pratt (W) | Jan. 12, 1850 | Mar. 3, 1857 | |
| 35th-37th | Anthony Kennedy (AmKN) | Mar. 4, 1857 | Mar. 3, 1863 | |
| 38th-40th | Reverdy Johnson (W, U, D) | Mar. 4, 1863 | Jul. 10, 1868 | Resigned |
| 40th | William P. Whyte (D) | Jul. 13, 1868 | Mar. 3, 1869 | Appointed |
| 41st-43rd | William T. Hamilton (D) | Mar. 4, 1869 | Mar. 3, 1875 | |
| 44th-46th | William P. Whyte (D) | Mar. 4, 1875 | Mar. 3, 1881 | |
| 47th-55th | Arthur P. Gorman (D) | Mar. 4, 1881 | Mar. 3, 1899 | |
| 56th-58th | Louis E. McComas (R) | Mar. 4, 1899 | Mar. 3, 1905 | |
| 59th-62nd | Isidor Rayner (D) | Mar. 4, 1905 | Nov. 25, 1912 | Died |
| 62nd-63rd | William P. Jackson (R) | Nov. 29, 1912 | Jan. 28, 1914 | Appointed |
| 63rd-64th | Blair Lee (D) | Jan. 28, 1914 | Mar. 3, 1917 | |
| 65th-67th | Joseph I. France (R) | Mar. 4, 1917 | Mar. 3, 1923 | |
| 68th-70th | William C. Bruce (D) | Mar. 4, 1923 | Mar. 3, 1929 | |
| 71st-73rd | Phillips L. Goldsborough (R) | Mar. 4, 1929 | Jan. 3, 1935 | |
| 74th-79th | George L. P. Radcliffe (D) | Jan. 3, 1935 | Jan. 3, 1947 | |
| 80th-82nd | Herbert R. O'Conor (D) | Jan. 3, 1947 | Jan. 3, 1953 | |
| 83rd-88th | James G. Beall (R) | Jan. 3, 1953 | Jan. 3, 1965 | |
| 89th-91st | Joseph D. Tydings (D) | Jan. 3, 1965 | Jan. 3, 1971 | |
| 92nd-94th | J. Glenn Beall, Jr. (R) | Jan. 3, 1971 | Jan. 3, 1977 | |
| 95th-109th | Paul S. Sarbanes (D) | Jan. 3, 1977 | Jan. 3, 2007 | |
| 110th-118th | Benjamin L. Cardin (D) | Jan. 3, 2007 | Jan. 3, 2025 | |
| 119th- | Angela D. Alsobrooks (D) | Jan. 3, 2025 | Present | |
| Class 3 | ||||
| 1st-5th | John Henry (Pro-Admin) | Mar. 4, 1789 | Jul. 10, 1797 | Resigned |
| 5th-6th | James Lloyd (F) | Dec. 8, 1797 | Dec. 1, 1800 | Resigned |
| 6th-7th | William Hindman (F)3 | Dec. 12, 1800 | Nov. 19, 1801 | |
| 7th-9th | Robert Wright (DR) | Nov. 19, 1801 | Nov. 12, 1806 | Resigned |
| 9th-12th | Philip Reed (DR) | Nov. 25, 1806 | Mar. 3, 1813 | |
| 13th-15th | Robert H. Goldsborough (F, AJ, W) | May 21, 1813 | Mar. 3, 1819 | |
| 16th-19th | Edward Lloyd (DR, CRR, J) | Dec. 27, 1819 | Jan. 14, 1826 | Resigned |
| 19th-23rd | Ezekiel F. Chambers (Adams) | Jan. 24, 1826 | Dec. 20, 1834 | Resigned |
| 23rd-24th | Robert H. Goldsborough (F, AJ, W) | Jan. 13, 1835 | Oct. 5, 1836 | Died |
| 24th-26th | John S. Spence (AJ, W) | Dec. 31, 1836 | Oct. 24, 1840 | Died |
| 26th-27th | John L. Kerr (W) | Jan. 5, 1841 | Mar. 3, 1843 | |
| 28th-37th | James A. Pearce (W, OP, D) | Mar. 4, 1843 | Dec. 20, 1862 | Died |
| 37th-39th | Thomas H. Hicks (U) | Dec. 29, 1862 | Feb. 14, 1865 | Appointed, then elected; died |
| 39th | John A. J. Creswell (UU) | Mar. 9, 1865 | Mar. 3, 1867 | |
| 40th-42nd | George Vickers (D)4 | Mar. 7, 1868 | Mar. 3, 1873 | |
| 43rd-45th | George R. Dennis (D) | Mar. 4, 1873 | Mar. 3, 1879 | |
| 46th-48th | James B. Groome (D) | Mar. 4, 1879 | Mar. 3, 1885 | |
| 49th-51st | Ephraim K. Wilson (D)5 | Mar. 4, 1885 | Feb. 24, 1891 | Died |
| 52nd-54th | Charles H. Gibson (D) | Nov. 19, 18916 | Mar. 3, 1897 | Appointed, then elected |
| 55th-57th | George L. Wellington (R) | Mar. 4, 1897 | Mar. 3, 1903 | |
| 58th-59th | Arthur P. Gorman (D) | Mar. 4, 1903 | Jun. 4, 1906 | Died |
| 59th-60th | William P. Whyte (D) | Jun. 8, 1906 | Mar. 17, 1908 | Appointed, then elected; died |
| 60th-66th | John W. Smith (D) | Mar. 25, 1908 | Mar. 3, 1921 | |
| 67th-69th | Ovington E. Weller (R) | Mar. 4, 1921 | Mar. 3, 1927 | |
| 70th-81st | Millard E. Tydings (D) | Mar. 4, 1927 | Jan. 3, 1951 | |
| 82nd-87th | John M. Butler (R) | Jan. 3, 1951 | Jan. 3, 1963 | |
| 88th-90th | Daniel B. Brewster (D) | Jan. 3, 1963 | Jan. 3, 1969 | |
| 91st-99th | Charles M. Mathias, Jr. (R) | Jan. 3, 1969 | Jan. 3, 1987 | |
| 100th-114th | Barbara A. Mikulski (D) | Jan. 3, 1987 | Jan. 3, 2017 | |
| 115th- | Chris Van Hollen (D) | Jan. 3, 2017 | Present | |
1. The state legislature failed to elect a candidate to fill the term before it adjourned, so the governor appointed Smith to fill the seat on Mar. 4, 1809. Smith asked the Senate to clarify his status—whether his credentials extended through the regular session of the Senate scheduled to begin on May 22, 1809, or if they terminated once the state legislature met again on June 5, 1809. The Senate decided that Smith would retain his seat during the session of the legislature, unless the assembly named a successor during that session. Smith was reelected by the state legislature on Nov. 16, 1809.
2. Vacancy from Mar. 4, 1815, to Jan. 28, 1816, because of failure of legislature to elect.
3. Hindman was elected in 1800 to fill the vacancy caused by the resignation of James Lloyd; at expiration of the term he was appointed to fill the vacancy caused by the failure of the legislature to elect his successor and served from December 12, 1800, to November 19, 1801; he was not a candidate for reelection.
4. Phillip F. Thomas was elected but was not permitted to qualify. Vacancy from Mar. 4, 1867, to Mar. 6, 1868.
5. Died Feb. 24, 1891. Had been reelected on Jan. 15, 1890, for the term beginning Mar. 4, 1891.
6. Vacancy from Feb. 25 to Nov. 18, 1891, because of recess of legislature.
