| Election Name: | 1840 Delaware gubernatorial election |
| Country: | Delaware |
| Type: | Presidential |
| Ongoing: | no |
| Previous Election: | 1836 Delaware gubernatorial election |
| Previous Year: | 1836 |
| Next Election: | 1844 Delaware gubernatorial election |
| Next Year: | 1844 |
| Election Date: | November 3, 1840 |
| Nominee1: | William B. Cooper |
| Party1: | Whig Party (United States) |
| Popular Vote1: | 5,850 |
| Percentage1: | 53.80% |
| Nominee2: | Warren B. Jefferson |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 5,024 |
| Percentage2: | 46.20% |
| Map Size: | 210px |
| Governor | |
| Before Election: | Cornelius Comegys |
| Before Party: | Whig Party (United States) |
| After Election: | William B. Cooper |
| After Party: | Whig Party (United States) |
The 1840 Delaware gubernatorial election was held on November 3, 1840. Whig Governor Cornelius Comegys was unable to seek re-election to a second term. Former State Representative William B. Cooper ran as the Whig nominee to succeed Comegys and faced Democratic nominee Warren B. Jefferson in the general election. Cooper won the largest victory in a gubernatorial election since 1819, and was ushered into office with a sizable Whig majority in the legislature.[1]