| Election Name: | 2005 Pittsburgh mayoral election |
| Flag Image: | Flag of Pittsburgh, Pennsylvania.svg |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 2001 Pittsburgh mayoral election |
| Previous Year: | 2001 |
| Next Election: | 2007 Pittsburgh mayoral special election |
| Next Year: | 2007 (special) |
| Election Date: | November 8, 2005 |
| Nominee1: | Bob O'Connor |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 40,226 |
| Percentage1: | 67.09% |
| Nominee2: | Joe Weinroth |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 16,321 |
| Percentage2: | 27.22% |
| Mayor | |
| Before Election: | Thomas J. Murphy, Jr. |
| Before Party: | Democratic Party (United States) |
| After Election: | Bob O'Connor |
| After Party: | Democratic Party (United States) |
The mayoral election of 2005 in Pittsburgh, Pennsylvania was held on Tuesday, November 8, 2005. The incumbent mayor, Tom Murphy of the Democratic Party chose not to run for what would have been a record fourth straight term.
Longtime City Councilman Bob O'Connor, who was defeated in the Democratic primary for mayor in the previous two elections, won nearly half the vote in a four-way contest. With outgoing executive Murphy deeply unpopular due to a 2003 budgetary crisis, O'Connor, a heated Murphy rival, emerged as the top candidate. His victory came against his legislative partner Bill Peduto (who would later become Mayor himself), City Controller Michael Lamb, and former Allegheny County Councilman Louis "Hop" Kendrick.
The general election was uncompetitive, as is the standard in heavily Democratic Pittsburgh, as O'Connor won by 40 points against Republican attorney Joe Weinroth. A total of 59,961 votes were cast.
Official campaign websites