Sir Sadiq Khan has said that the people of New York chose "hope over fear" by electing their new mayor, "just as Londoners did".
Zohran Mamdani made history on Tuesday night by becoming New York City's first Muslim and South Asian mayor and the youngest mayor since 1892.
The Mayor of London celebrated Mamdani's victory, drawing parallels with his own political success, while also taking aim at US President Donald Trump and his mayoral predecessor Boris Johnson.
Sir Sadiq said: "The people of New York had a clear choice – between hope and fear – and as we saw in London – hope won."
He added: "Huge congratulations to @ZohranKMamdani on his historic campaign."
The two mayors appear to have several things in common: both are social democrats and both have made history by becoming the first Muslim mayors of London and New York.
Both also appear to share a similar stance on Donald Trump.
Mamdani was elected even after Trump urged New Yorkers to vote for Republican Andrew Cuomo in the mayoral election and threatened to cut off funding to New York City if he won.
In his victory speech, Mamdani directly challenged Trump, telling him to "turn up the volume" and then saying he would "end the culture of corruption that made him possible".
Sir Sadiq has a long history of strained relations with the US President.
In 2019, Trump called him a "total loser," while Sir Sadiq said Trump was promoting far-right politics.
More recently, Trump called Sir Sadiq "a very bad mayor," to which Sir Sadiq responded by calling Trump "racist, sexist, misogynistic and Islamophobic." Speaking from London, he said: “People are wondering what it is about this Muslim mayor who leads a liberal, multicultural, progressive and successful city that means I’m living rent-free in Donald Trump’s head.”
In his role as Mayor of London, Sir Sadiq met with then-Mayor of New York City, Eric Adams, during a trip to the US in 2022, who referred to him as a “rockstar mayor.”