He issued a statement after being questions in a public meeting by Conservative assembly member Keith Prince, who cited this newspaper’s reporting.
Tribunal judges accepted that a control room in Finchley Road, Swiss Cottage, had been a “toxic environment” where one Asian man was subjected to constant racist “jokes”, including being asked whether he had a bomb in his bag.
Another complainant, of Caribbean heritage, was the victim of false allegations by colleagues, which the judges found were due to his race.
The tribunal was brought against Arriva London Rail (ARL), which has run London Overground since 2016 under a seven-and-a-half-year deal with TFL.
City Hall initially refused to provide any response from mayor Sadiq Khan, saying the incidents at the Swiss Cottage office, called Overground House, were an ARL issue, not a London Overground issue.
But Havering and Redbridge assembly member Keith Prince, who frequently raises transport-related issues at Mayor’s Question Time, questioned Mr Khan at City Hall on Thursday, November 17.
“Are you aware of the recent employment tribunal which found that there was a culture of racist bullying at the London Overground headquarters, run by Arriva Rail?” asked Mr Prince.
“Mr Mayor, will you condemn this and what will you do to drive these practices out and ensure a cultural change at London Overground?”
Mr Khan responded: “I wasn’t aware of that tribunal case but if that is the finding, of course I condemn it.”
Mr Khan said he suspected his press office had refused to respond “because I was a bit distracted yesterday on other issues”.
“I hadn’t seen the tribunal judgement,” he said. “But it’s a serious issue.”