The outcome puts a 43-year-old lawmaker best known for his irreverent jibes and disheveled mop of blond hair at the helm of one of Europe’s pre-eminent cities and host of the 2012 Olympic Games.

“I do not for one minute believe that this election shows that London has been transformed overnight into a Conservative city,” Johnson said. “But I do hope that it does show that the Conservatives have changed into a party that can again be trusted after 30 years with the greatest, most cosmopolitan . . . city on earth.”

The voting, a combination of voters’ first and second preferences, gave Johnson 1,168,738 votes, to incumbent Ken Livingstone’s 1,028,966.

Johnson was born Alexander Boris de Pfeffel Johnson in New York to English parents. Till recently, he was an American citizen.

Of Turkish descent, Johnson’s great-grandfather, Ali Kemal, a Turkish journalist, was briefly interior minister in the government of Ahmed Tevfik Pasha, Grand Vizier of the Ottoman Empire. His grandfather Osman Ali settled in the UK in the 1920s and changed his name to Wilfred Johnson.

He is married to barrister Marina Wheeler, daughter of legendary BBC journalist Charles Wheeler and his Sikh Indian wife.

Johnson, who was a reporter in The Times and other newspapers before becoming editor of the Spectator, became widely popular across Britain from his humorous appearances on a popular TV news quiz show; he is famous for riding around London on his bicycle while talking on his cellphone.

“Just as I will never vote to ban hunting, so I will never vote to abolish the free-born Englishman’s time-hallowed and immemorial custom, dating back as far as 1990 or so, of cycling while talking on a mobile,” he wrote when a law was proposed banning the practice.

Johnson reined in his mischievous side in a largely subdued campaign in which he called for cracking down on the city’s burgeoning wave of youthful gun and knife crime, scrapping the unpopular articulated buses he calls “18-metre-long socialist frankfurter buses,” and canceling a planned charge of $50 a day for drivers of high-carbon-emissions vehicles entering the central city.

Still, many Londoners are put off by his bumbling, buffoonlike persona.

“He’s like a clown . . . he’s an absolute joke,” said London resident Jim O’Hagen, 19.

Johnson said he would move to allay voters’ concerns. “I know there will be many whose pencils hovered for an instant before putting an X in my box,” he said. “I will work flat out to regain and to justify your confidence.”

In turning out Livingstone, a fixture in London leftist politics since the 1970s, voters joined a tide across England and Wales that saw the Labour Party lose 331 of more than 3,900 local council seats up for grabs, slipping to third place by receiving just 24 percent of the votes cast, behind the Conservatives, with 44 percent, and the Liberal Democrats, with 25 percent. The remaining votes were split among several smaller parties.

Losing the mayorship of London and its 7.2 million residents to the Conservatives for the first time since the post was created in 2000 was a significant symbolic blow to the ruling party, which analysts said would give the Tories a valuable platform from which to challenge Labor in the next national elections, expected probably in 2010.

The balloting was seen as a dismal referendum on the government of Prime Minister Gordon Brown, whose support has ebbed as Britain has slipped toward an economic downturn.

Gag reflex

He’s also well-known for his funny and audacious quotes. A sampling:

• On ethnicity, making a reference to his wife being half-Indian: “I’m down with the ethnics. You can’t out-ethnic me . . . my children are a quarter Indian, so put that in your pipe and smoke it.”

• On his political ambitions: “My chances of being PM are about as good as the chances of finding Elvis on Mars, or my being reincarnated as an olive.”

• On US President George W. Bush: “He liberated Iraq. It is good enough for me.”