The three finalists vying to become host city for the 2020 Olympics made their final presentations Saturday. It was a tight race that was decided by only a few votes.
Istanbul, Madrid and Tokyo were each given 45 minutes to make their final pitch to the IOC.
Tokyo defeated Istanbul 60-36 in the final round of secret voting by the International Olympic Committee. Madrid was eliminated earlier after an initial tie with Istanbul.
Tokyo, which hosted the 1964 Olympics, billed itself as the reliable choice at a time of global political and economic uncertainty - a message that resonated with the IOC.
"Tokyo can be trusted to be the safe pair of hands and much more," bid leader and IOC member Tsunekazu Takeda said in the final presentation. "Our case today is simple. Vote for Tokyo and you vote for guaranteed delivery. ... Tokyo is the right partner at the right time."
Tokyo had been on the defensive in the final days of the campaign because of mounting concerns over the leak of radioactive water from the tsunami-crippled Fukushima nuclear plant.
In the final presentation, Japanese Prime Minister Shinzo Abe gave the IOC assurances that the Fukushima leak was not a threat to Tokyo and took personal responsibility for keeping the games safe.
"Let me assure you the situation is under control," Abe said. "It has never done and will never do any damage to Tokyo."
Abe gave further assurances when pressed on the issue by Norwegian IOC member Gerhard Heiberg.
"It poses no problem whatsoever," Abe said in Japanese, adding that the contamination was limited to a small area and had been "completely blocked."
"There are no health related problems until now, nor will there be in the future," he said. "I make the statement to you in the most emphatic and unequivocal way."
Tokyo Electric Power Co., Fukushima's operator, has acknowledged that tons of radioactive water has been seeping into the Pacific from the plant for more than two years after the March 2011 earthquake and tsunami led to meltdowns at three of its reactors. Recent leaks from tanks storing radioactive water used to cool the reactors have added to fears that the amount of contaminated water is getting out of hand.
With Madrid's bid dogged by questions over Spain's economic crisis and Istanbul handicapped by political unrest and the civil war in neighboring Syria, Tokyo proved to be the least risky choice for the IOC.
"I think it was a choice between going to new shores and staying with a more traditional candidate," IOC vice president Thomas Bach said. "And this time they decided with the more traditional candidate."
IOC members have also been concerned about construction delays and other challenges plaguing preparations for the 2016 Olympics in Rio de Janeiro. Opting for certainty in 2020 was a key priority.
"I think very much that could have been a factor," Bach said.
Tokyo delegates in the hall screamed with joy, jumped in the air, hugged and waved small flags after Rogge opened a sealed envelope and read the words: "The International Olympic Committee has the honor of announcing that the games of the 32nd Olympiad in 2020 are awarded to the city of Tokyo."
Even though it was 5 a.m. Sunday in Japan, about 1,200 dignitaries and Olympic athletes who crowded into a convention hall in downtown Tokyo celebrated the news. Cheers of "Banzai!" filled the hall when the announcement was made.
The Associated Press contributed to this report.