Ohio was admitted to the Union on March 1, 1803, and elects U.S. senators to class 1 and class 3. Its current U.S. senators are Republicans Bernie Moreno and Jon Husted (both serving since 2025). John Sherman was Ohio's longest-serving senator (1861–1877; 1881–1897).
List of senators
|- style="height:2em"
! rowspan=3 | 1
| rowspan=3 align=left | John Smith<br />
| rowspan=3 | Democratic-<br>Republican
| rowspan=3 nowrap | Apr 1, 1803 –<br/>Apr 25, 1808
| rowspan=3 | Elected in 1803.Resigned.
| rowspan=5 | 1
|
| rowspan=2 | 1
| rowspan=2 | Elected in 1803.Resigned.
| rowspan=3 nowrap | Mar 4, 1807 –<br/>Mar 3, 1809
| rowspan=3 | Democratic-<br>Republican
| rowspan=3 align=right | 100px<br/>Edward Tiffin<br />
! rowspan=3 | 2
|- style="height:2em"
| colspan=3 | Vacant
| nowrap | Apr 25, 1808 –<br/>Dec 12, 1808
|
|- style="height:2em"
! rowspan=3 | 2
| rowspan=3 align=left | 100px<br/>Return J. Meigs Jr.<br />
| rowspan=3 | Democratic-<br>Republican
| rowspan=3 nowrap | Dec 12, 1808 –<br/>Dec 8, 1810
| Elected in 1808 to finish Smith's term.
|- style="height:2em"
| rowspan=2 | Elected in 1808 to full term.
| rowspan=3 nowrap | Mar 4, 1891 –<br/>Mar 3, 1897
| rowspan=3 | Democratic
| rowspan=3 align=right | 100px<br/>Calvin S. Brice<br />
! rowspan=3 | 19
|- style="height:2em"
| rowspan=3 | Re-elected in 1892.Resigned to become U.S. Secretary of State.
| rowspan=4 | 16
|
|- style="height:2em"
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|- style="height:2em"
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| rowspan=4 | 17
| rowspan=4 | Elected in 1896.
| rowspan=9 nowrap | Mar 4, 1897 –<br/>Mar 3, 1909
| rowspan=9 | Republican
| rowspan=9 align=right | 100px<br/>Joseph B. Foraker<br />
! rowspan=9 | 20
|- style="height:2em"
! rowspan=4 | 13
| rowspan=4 align=left | 100px<br/>Mark Hanna<br />
| rowspan=4 | Republican
| rowspan=4 nowrap | Mar 5, 1897 –<br/>Feb 15, 1904
| Appointed to continue Sherman's term.Elected in 1898 to finish Sherman's term.
|- style="height:2em"
| rowspan=3 | Elected in 1898 to the next term.Died.
| rowspan=5 | 17
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|- style="height:2em"
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|- style="height:2em"
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| rowspan=5 | 18
| rowspan=5 | Re-elected in 1902.Retired.
|- style="height:2em"
| colspan=3 | Vacant
| nowrap | Feb 15, 1904 –<br/>Mar 23, 1904
|
|- style="height:2em"
! rowspan=4 | 14
| rowspan=4 align=left | 100px<br/>Charles W. F. Dick<br />
| rowspan=4 | Republican
| rowspan=4 nowrap | Mar 23, 1904 –<br/>Mar 3, 1911
| Elected in 1904 to finish Hanna's term.
|- style="height:2em"
| rowspan=3 | Elected in 1904 to the next term.Lost re-election.
| rowspan=3 | 18
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|- style="height:2em"
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|- style="height:2em"
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| rowspan=3 | 19
| rowspan=3 | Elected Jan 12, 1909.