| Election Name: | 1840 Philadelphia mayoral election |
| Type: | presidential |
| Ongoing: | no |
| Previous Year: | 1839 |
| Next Year: | 1841 |
| Image1: | John-Swift-Mayor-of-Philadelphia-e1486412581340 (1).jpg |
| Nominee1: | John Swift |
| Popular Vote1: | 6,355 |
| Percentage1: | 56.87% |
| Nominee2: | Henry Horn |
| Popular Vote2: | 4,820 |
| Percentage2: | 43.13% |
| Mayor | |
| Before Party: | Whig Party (United States) |
| After Party: | Whig Party (United States) |
The 1840 Philadelphia mayoral election saw John Swift reelected to office for his eighth overall non-consecutive term.
This was the first Philadelphia mayoral election in which the mayor wound up being solely elected by the general public. Since Swift received a majority in the general election, the City Council did not select the mayor. Beginning in 1839, the city operated under a mixed electoral system. Citizens voted for mayor in a general election. If a candidate receive a majority of the vote, they would be elected mayor. However, if no candidate received a majority, the City Council would select a mayor from the top-two finishers.