The 2025 Buffalo mayoral election will be held on November 4, 2025, to elect the mayor of Buffalo, New York. 
Incumbent acting mayor Christopher Scanlon, who took office upon the resignation of Byron Brown, ran for a full term but lost the Democratic primary to state senator Sean Ryan. The Republican Party nominated former county assistant district attorney James Gardner, while Buffalo ReUse founder Michael Gainer is running as an independent. 
Background.
In anticipation of mayor Byron Brown stepping down to join the private sector, South Buffalo councilman Christopher Scanlon was elected president of the Buffalo Common Council by a council vote on January 2, 2024. Scanlon had organized Brown's write-in campaign for the 2021 Buffalo mayoral election that won him a fifth term. Brown resigned to become chief executive officer of Western Regional Off-Track Betting on October 15, 2024, making Scanlon the acting mayor through right of succession to serve out his remaining term.
Democratic primary.
State senator Sean Ryan was endorsed by the Erie County Democratic Committee on February 22, 2025. The endorsement process faced criticism, as committee chairman Jeremy Zellner announced Ryan's endorsement several days before a vote was held among membership. Zellner denied rumors that he had pushed for Ryan's endorsement in exchange for being appointed to Ryan's state senate seat if he won mayorship. As both party chairman and self-appointed Erie County board of elections commissioner, Zellner has been accused of having a conflict of interest with regards to elections and nominating petitions. Four candidates alleged impropriety in the endorsement process: Buffalo ReUse founder Michael Gainer, acting mayor Christopher Scanlon, former Buffalo Fire commisioner Garnell Whitfield, and common councilor Rasheed Wyatt.
Michael Gainer was disqualified from the primary after Sean Ryan sued him in New York Supreme Court, alleging his nominating petition contained fraud. Gainer then successfully petitioned to run as an independent candidate in the general election, and he will appear on the Restore Buffalo line. Christopher Scanlon also completed an independent petition for the general election. Garnell Whitfield's petition for an independent line was disqualified by the Erie County board of elections after a challenge by Scanlon's campaign.
Frontrunners Sean Ryan and Christopher Scanlon both launched attack ads against each other in the leadup to the primary. Ryan's ads accused Scanlon of accepting donations from Republican Carl Paladino, while Scanlon's ads accused Ryan of endorsing 2021 candidate India Walton and her platform to defund the police.
Sean Ryan won the Democratic primary on June 24, 2025. 27% of registered Democrats cast ballots, which was a higher voter turnout than the 2021 primary. 7,500 ballots were cast during the nine-day early voting period, up from 2,684 in 2021. Christopher Scanlon withdrew his independent bid following the primary and announced he would return to the Buffalo Common Council presidency, ensuring a new mayor would be decided in the general election.
Republican nomination.
James Gardner was initially reported as being a placeholder candidate who would later give up his ballot line after the party nominated him to a judgeship in Yonkers. He denied those claims, and declared his intention to compete in the general election. Erie County clerk Michael Kearns has reportedly offered to replace Gardner on the ballot.
Working Families nomination.
The Working Families Party clarified that their nomination of Sean Ryan was contingent on him winning the Democratic primary. They reserved the right to rescind their nomination should he have lost, as the party historically does not endorse spoiler candidates. Ryan also said he would have dropped out of the mayoral race if he lost the Democratic primary.
Conservative nomination.
James Gardner has worked as a civil attorney for the law firm of Erie County Conservative Party chairman Ralph C. Lorigo since January 2025.
Independent candidates.
Michael Gainer and Christopher Scanlon filed independent petitions to run in the general election under new party lines, ensuring they would be able to continue their campaigns even if they failed to secure the Democratic nomination. Garnell Whitfield's independent petition was disqualified by the Erie County board of elections after a challenge by Scanlon's campaign. Scanlon announced that he was withdrawing his independent candidacy, and would instead return to serving as Buffalo Common Council president.