Sadiq Khan chose a Jewish community Holocaust commemoration as the first public event of his mayoralty.
He joined thousands at Barnet Copthall stadium, home of Saracens Rugby Club, to mark Yom HaShoah – the Jewish Community’s Holocaust Remembrance Day.
Speakers at the event included Holocaust survivor Ben Helfgott and the Chief Rabbi Ephraim Mirvis.
The attendance of Mr Khan comes at a time when the Labour Party is accused of anti-semitism within its ranks.
He added his visit was "far, far bigger, and far more important than the Labour Party".