| Election Name: | 1834 Illinois gubernatorial election |
| Country: | Illinois |
| Type: | presidential |
| Ongoing: | Yes |
| Previous Election: | 1830 Illinois gubernatorial election |
| Previous Year: | 1830 |
| Next Election: | 1838 Illinois gubernatorial election |
| Next Year: | 1838 |
| Election Date: | August 4, 1834 |
| Image1: | Joseph Duncan (cropped).png |
| Nominee1: | Joseph Duncan |
| Party1: | Democratic |
| Popular Vote1: | 17,349 |
| Percentage1: | 52.93% |
| Nominee2: | William Kinney |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 10,229 |
| Percentage2: | 31.21% |
| Image3: | 3x4.svg |
| Nominee3: | Robert K. McLaughlin |
| Party3: | Democratic Party (United States) |
| Popular Vote3: | 4,315 |
| Percentage3: | 13.16% |
| Map Size: | 150px |
| Governor | |
| Before Election: | William Lee D. Ewing |
| Before Party: | Democratic Party (United States) |
| After Election: | Joseph Duncan |
| After Party: | Whig |
The 1834 Illinois gubernatorial election was the fifth quadrennial election for this office. U.S. Representative Joseph Duncan was elected by a majority of the voters. He defeated former Lt. Governor William Kinney and former state treasurer Robert K. McLaughlin.
Duncan was a member of the Democratic Party for most of his early career, but fell out with party leader and President Andrew Jackson during Jackson's first term.[1] He did not announce his change in party affiliation publicly, allowing his votes against Jackson in Congress to relay the message, but news of Duncan's change in affiliation did not reach most Illinois voters and politicians until after the election, resulting in Duncan's nomination and election as a Democrat.
Duncan did not return to the state from Washington, D.C. until after the election. This was the only election of a Whig Governor in Illinois history, albeit by accident on the part of voters.