Ken Welch defeated Robert Blackmon in the general election for mayor of St. Petersburg, Florida. This was the first open race for mayor of St. Petersburg since 2009. Welch, a Pinellas County Commissioner from 2000 to 2020, was endorsed by incumbent Mayor Rick Kriseman (D). Though the race is officially nonpartisan, Welch is a registered Democrat. The last Republican to serve as mayor of St. Petersburg was Bill Foster from 2010 to 2014. 

Welch and Blackmon were the two top finishers in the Aug. 24 primary with 39.1% and 28.6% of the vote, respectively. They advanced to the general election since no candidate won more than 50% of the vote. 

According to campaign finance reports through Oct. 28, Welch raised $503,336 and spent $462,588, while Blackmon raised $307,990 and spent $291,526. 

St. Petersburg is one of 17 of the 100 largest U.S. cities by population that held general elections for mayor on Nov. 2. In total, 28 top-100 cities are electing mayors in 2021. Heading into election day, 63 top-100 mayors were affiliated with the Democratic Party, 26 were affiliated with the Republican Party, four are independents, six identify as nonpartisan or unaffiliated, and one mayor has not responded to inquiries about his partisan affiliation.