| Portrait | Mayor | Party | Sworn in | Left office | Comments |
| 1 | | Solomon Juneau
| Democrat | 1846 | 1846 | |
| 2 | | Horatio Wells
| Democrat | 1847 | 1847 | |
| 3 | | Byron Kilbourn
| Democrat | 1848 | 1848 | |
| 4 | | Don A. J. Upham
| Democrat | 1849 | 1850 | |
| 5 | | George H. Walker
| Democrat | 1851 | 1851 | |
| 6 | | Hans Crocker
| Democrat | 1852 | 1852 | |
| 7 | | George H. Walker
| Democrat | 1853 | 1853 | His second, nonconsecutive term |
| 8 | | Byron Kilbourn
| Democrat | 1854 | 1854 | His second, nonconsecutive term |
| 9 | | James B. Cross
| Democrat | 1855 | 1857 | |
| 10 | | William A. Prentiss
| Republican | 1858 | 1859 | |
| 11 | | Herman L. Page
| Democrat | 1859 | 1859 | |
| 12 | | William Pitt Lynde
| Democrat | 1860 | 1860 | |
| 13 | | James S. Brown
| Democrat | 1861 | 1861 | Elected without opposition. Did not run for re-election. |
| 14 | | Horace Chase
| Democrat | 1862 | 1862 | |
| 15 | | Edward O'Neill
| Democrat | 1863 | 1863 | |
| 16 | | Abner Kirby
| Democrat | 1864 | 1864 | |
| 17 | | John J. Tallmadge
| Democrat | 1865 | 1866 | |
| 18 | | Edward O'Neill
| Democrat | 1867 | 1870 | His second, nonconsecutive term |
| 19 | | Joseph Phillips
| Democrat | 1870 | 1871 | |
| 20 | | Harrison Ludington
| Republican | 1871 | 1872 | |
| 21 | | David G. Hooker
| Democrat | 1872 | 1873 | |
| 22 | | Harrison Ludington
| Republican | 1873 | 1876 | His second, nonconsecutive term |
| 23 | | Ammi R. R. Butler
| Democrat | 1876 | 1878 | |
| 24 | | John Black
| Democrat | 1878 | 1880 | |
| 25 | | Thomas H. Brown
| Republican | 1880 | 1882 | |
| 26 | | John M. Stowell
| Democrat | 1882 | 1884 | |
| 27 | | Emil Wallber
| Republican | 1884 | 1888 | |
| 28 | | Thomas H. Brown
| Republican | 1888 | 1890 | His second, nonconsecutive term |
| 29 | | George W. Peck
| Democrat | 1890 | November 11, 1890 | Resigned to become Governor of Wisconsin |
| 30 | | Peter J. Somers
| Democrat | December 6, 1890 | June 5, 1893 | Resigned after being elected to the House of Representatives |
| – | | Henry Hase
| | June 5, 1893 | July 1, 1893 | Acting Mayor |
| 31 | | John C. Koch
| Republican | 1893 | 1896 | |
| 32 | | William C. Rauschenberger
| Republican | 1896 | 1898 | |
| 33 | | David S. Rose
| Democrat | 1898 | 1906 | |
| 34 | | Sherburn M. Becker
| Republican | 1906 | 1908 | |
| 35 | | David S. Rose
| Democrat | 1908 | 1910 | His second, nonconsecutive term |
| 36 | | Emil Seidel
| Socialist | 1910 | 1912 | |
| 37 | | Gerhard A. Bading
| Republican-Democrat Fusion | 1912 | 1916 | |
| 38 | | Daniel Hoan
| Socialist | 1916 | April 16, 1940 | |
| 39 | | Carl Zeidler
| Democrat | April 16, 1940 | April 8, 1942 | Resigned to fight in World War II, in which he was killed |
| 40 | | John Bohn
| Nonpartisan | April 8, 1942 | April 20, 1948 | Interim mayor until being officially elected in 1944 |
| 41 | | Frank Zeidler
| Socialist | April 20, 1948 | April 19, 1960 | |
| 42 | | Henry Maier
| Democrat | April 19, 1960 | April 19, 1988 | |
| 43 | | John Norquist
| Democrat | April 18, 1988 | January 1, 2004 | Resigned to head the Congress for the New Urbanism |
| | Marvin Pratt
| Democrat | January 1, 2004 | April 20, 2004 | Acting mayor, first African American mayor of Milwaukee |
| 44 | | Tom Barrett
| Democrat | April 20, 2004 | December 22, 2021 | Resigned to become U.S. Ambassador to Luxembourg |
| 45 | | Cavalier Johnson
| Democrat | December 22, 2021 | present | First elected African American mayor of Milwaukee |