2018 San Francisco mayoral special election

A special election was held for Mayor of San Francisco on June 5, 2018, to fill the remainder of the term of Ed Lee, who had died in office on December 12, 2017. Upon Lee's death, London Breed (who was, at the time, President of the San Francisco Board of Supervisors), became Acting Mayor of San Francisco, but a vote of six supervisors replaced Breed with Supervisor Mark Farrell. The mayoral election was held concurrently with the statewide direct primary election. In San Francisco, the election for the eighth district member of the board of supervisors was also on the ballot.

Eight candidates qualified to appear on the ballot and a ninth qualified as a write-in. The four major candidates were London Breed, former Supervisor Angela Alioto, San Francisco District 6 Supervisor Jane Kim, and former state senator Mark Leno. All four main candidates identified as Democrats, though the position is officially nonpartisan per the Constitution of California. The election was won by Breed, with Leno conceding the election on June 13.