Sadiq Khan has attacked David Cameron and defeated London mayoral opponent Zac Goldsmith for running a campaign "straight out of the Donald Trump playbook".
The newly elected Labour mayor, writing in the Observer, accused the pair of using "fear and innuendo to try to turn different ethnic and religious groups against each other".
He said the Conservative Party’s mayoral campaign attempted to "divide London’s communities".
Mr Khan won more than 1.3 million votes once second preference votes were counted, the biggest mandate for a single candidate in British electoral history.
His main rival Goldsmith secured just under one million votes – 13% down.
The Conservative campaign was marred by accusations it was using fear to try to retain control of City Hall, with the prime minister raising questions about Mr Khan's suitability for mayor in the Commons.
Baroness Sayeeda Warsi - a former party chair who was the UK's first female Muslim cabinet minister - said the election defeat was due to a "dog whistle campaign".
She added the "appalling" campaign had "lost us the election, our reputation and credibility on issues of race and religion".
Defence Secretary Michael Fallon said on Saturday that "stuff gets said during elections, questions get posed", and called the campaign "the rough and tumble of politics".
Donald Trump, who is the presumptive Republican nominee in the US presidential race, has been dogged by criticism for a series of controversial policies including a ban on Muslims entering the country and proposals to build a wall on the border with Mexico.