| Election Name: | 1940 Illinois gubernatorial election |
| Country: | Illinois |
| Flag Year: | 1915 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1936 Illinois gubernatorial elections |
| Previous Year: | 1936 |
| Election Date: | November 5, 1940 |
| Next Election: | 1944 Illinois gubernatorial elections |
| Next Year: | 1944 |
| Image1: | File:Dwight H. Green cph.3b30070 (1).jpg |
| Nominee1: | Dwight H. Green |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 2,197,778 |
| Percentage1: | 52.93% |
| Nominee2: | Harry B. Hershey |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 1,940,833 |
| Percentage2: | 46.74% |
| Map Size: | 300px |
| Governor | |
| Before Election: | Henry Horner (before primary) Democratic John Henry Stelle (before general election) Democratic |
| After Election: | Dwight H. Green |
| After Party: | Republican Party (United States) |
Before the primary, incumbent governor Henry Horner, a Democrat, opted not to seek a third term. In October, before the general election, his death in office made John Henry Stelle assume the governorship. However, Stelle had previously failed to win the Democratic nomination in the primary.
Republican Dwight H. Green won the election.