The historic annulment comes after Mr. Odinga filed a petition claiming the electronic voting results were hacked into and rigged in favour of President Uhuru Kenyatta.
Kenyatta's lawyer, Ahmednasir Abdullahi, faulted the verdict of the court and described it as a political decision.
Following the decision by the Supreme Court judges to annul the re-election of President Kenyatta, Jubilee supporters remained calm as they pondered the judgement. Kenyans now hope the repeat election will help determine who the most preferred candidate is.
Unsurprisingly Mr Kenyatta was less enthusiastic, saying of the judges that "six people have decided they will go against the will of the people".
Kenyatta was announced the victor of the ballot held in August with 54% of the vote.
The ruling, which was broadcast to a stunned nation on national television, sets up a new race for the presidency between Uhuru Kenyatta and veteran opponent Raila Odinga. "This is a precedent-setting ruling", he said.
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Kenya is the first African country to have a presidential poll invalidated by a court.
"The first respondent (the election board) failed, neglected or refused to conduct the presidential election in a manner consistent with the dictates of the constitution".
"The presidential election held on August 8 was not conducted in accordance with the constitution and applicable law, rendering the results invalid, null and void", he said. It ordered a new poll within 60 days.
The election sparked days of protests, in which at least 28 people were killed.
Mr Kenyatta said that while he "personally disagrees" with the ruling that nullifies his win, he respects it.
The court did not place any blame on Kenyatta or his party.
Numbers of the Day: 18500 people
Myanmar security forces have been clashing with the Rohingya since August 25, when Rohingya insurgents attacked police outposts. Islam said his team of border guards are intercepting the Rohingyas arriving in Bangladesh to "prevent the illegal intrusion".
Odinga said he would challenge the results in the Supreme Court.
As news of the court's decision spread, cheers and celebrations could be heard on the streets in parts of the capital, Nairobi.
Odinga has contested the last three presidential polls and lost all of them.
The country was ravaged by post election violence in 2007, which left 1,200 people dead and another 600,000 displaced.
The AU Commission, in collaboration with regional economic communities/regional mechanisms, will continue to closely monitor the electoral process with a view to ensuring that the will of the Kenyan people is fully respected, the statement read.
Texans-Cowboys game canceled after being moved from floods
The Cowboys said ticket buyers can choose to either get a refund or have the money donated to Hurricane Harvey relief. Watt was asked Monday whether the game should be cancelled entirely, he said there were "much bigger things at hand".