| Election Name: | 2018 Ohio Senate election |
| Majority Seats: | 17 |
| Leader1: | Larry Obhof |
| Country: | Ohio |
| Before Party: | Republican Party (United States) |
| Before Election: | Larry Obhof |
| After Party: | Republican Party (United States) |
| After Election: | Larry Obhof |
| Ongoing: | no |
| Leaders Seat1: | District 22 |
| Map Size: | 250px |
| Swing1: | 7.17% |
| Swing2: | 6.84% |
| Leader2: | Kenny Yuko |
| Leaders Seat2: | District 25 |
| Percentage1: | 47.26% |
| Previous Year: | 2016 |
| President of the Ohio Senate | |
| Seats For Election: | 17 seats from odd-numbered districts in the Ohio Senate |
| Seats Before2: | 9 |
| Seats Before1: | 24 |
| Seats After2: | 9 |
| Seats After1: | 24 |
| Previous Election: | 2016 Ohio Senate Election |
| Next Election: | 2020 Ohio Senate election |
| Popular Vote2: | 1,145,439 |
| Popular Vote1: | 1,032,867 |
| Percentage2: | 52.41% |
| Party2: | Democratic Party (United States) |
| Type: | legislative |
| Party1: | Republican Party (United States) |
| Next Year: | 2020 |
| Turnout: | 55.8% (15.1pp) |
The 2018 Ohio Senate election was held on November 6, 2018, with the primary election held on May 8, 2018. Ohio voters elected state senators in the 17 odd-numbered Ohio Senate districts. State senators elected in 2018 are eligible to serve a four-year term beginning January 2019 and ending December 2022. These elections coincided with elections for Ohio Governor, the Ohio House, the U.S. House of Representatives, the U.S. Senate, and other statewide offices.
Despite a moderate statewide swing that allowed the Democrats to win the popular vote, the Republicans retained their supermajority of 24 seats in the Senate, compared to the Democrats' 9 seats.
| Party | Candidates | Votes | Seats Won | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. | % | +/– | No. | +/– | % | ||||
| Republican Party | 17 | 1,032,867 | 47.26 | 7.17 | 10 | 0 | 58.82 | ||
| Democratic Party | 17 | 1,145,439 | 52.41 | 6.84 | 7 | 0 | 41.18 | ||
| Libertarian Party | 1 | 4,037 | 0.18 | 0.18 | 0 | 0 | 0.00 | ||
| Green Party | 1 | 3,041 | 0.14 | 0.14 | 0 | 0 | 0.00 | ||
| Total | 36 | 100.00 | 17 | 100.00 | |||||
|}
| District 1 • District 3 • District 5 • District 7 • District 9 • District 11 • District 13 • District 15 • District 17 • District 19 • District 21 • District 23 • District 25 • District 27 • District 29 • District 31 • District 33 |