Boris Johnson has unseated Ken Livingstone, winning 53 per cent of second-round votes to become London's new mayor.
The Conservative candidate had to rely on second preference votes but won through, finishing with 1,168,738 votes compared to Mr Livingstone's 1,028,966.
Liberal Democrat candidate Brian Paddick won 236,685 first-preference votes and came third, while Green party candidate Sian Berry took fourth place with 77,374 votes.
But it was Mr Johnson's night and, clearly delighted, he told City Hall he planned to "get cracking" from tomorrow in changing the city.
"I know there will be many whose pencils hovered for an instant before putting their 'x' in my box," he said.
"I will work flat out to repay and justify your confidence."
He added he was determined to "dispel some of the myths that have been created for me" and pressed his belief that the Conservatives "have changed into a party that can again be trusted".
Mr Johnson paid tribute to Mr Livingstone as a "very considerable public servant" and, in his concession speech, the ousted mayor said he would do "all I can to help the new administration".
"It has been the most amazing experience. This is the most amazing city," Mr Livingstone said.
"In whatever role, I will continue while I live and breathe to live in this city, to love this city, and to work to make it better."
Delays in the announcement of the result, which had been initially anticipated on Friday afternoon, were due to a combination of technical difficulties, spoilt ballot papers and an unexpectedly high turnout.
Forty-five per cent of the electorate participated in the mayoral vote, a major increase on the 34 per cent seen in 2004.
Tonight's result means the end of Mr Livingstone's eight-year tenure in City Hall and marks the first return of the Tories to a high executive position for the first time since John Major's general election victory in 1992.