The ruling paves the way for Kenyatta to be sworn in on November 28.
However, turnout appears headed for a record low of around 35 percent, tarnishing the credibility of an election that has deeply polarised east Africa's economic powerhouse.
Uhuru Kenyatta on Monday threatens to remove opposition leader should he be elected in Oct. 17 presidential election
The robes judges wear make them think they are superior to other Kenyans, charges Uhuru Kenyatta
"We have one person killed and four others admitted in hospital with gunshot injuries," said Dr Ojwang Lusi, the regional health chief in western Kisumu county.
Kenya's election commission declares Uhuru Kenyatta winner amid post-election violence
Uhuru Kenyatta gets formally endorsed as presidential candidate by the ruling Jubilee Party
Kenya is already gripped by election fever and primaries to choose candidates for local government and parliament have seen violence and dramatic last-minute floor-crossings.
A 1.8 billion euro trust fund to be established in Kenya to address the refugee crisis and provide work opportunities for youth
Prosecutors dropped charges of crimes against humanity against Kenyatta in December.
A Kenyan lawmaker was shot dead in the capital early on Saturday morning
The coalition said in a statement it would work on developing a roadmap "towards the ultimate merger into the new political outfit".
Since independence in 1963, Kenya has never had a published foreign or diaspora policy
Kenyan authorities are currently investigating the killing of Yebei, who after his dismissal by prosecutors was summoned by Ruto's lawyers as a "crucial" defence witness
Ruto's lawyer Karim Khan said Yebei was a "critical witness to the defence" and had been referred to the ICC's victims and witness unit because of the risk "we believe he faced".
Kenyatta said his choice to be the next Inspector General of Police, Joseph Boinett, had "in-depth knowledge in strategic and security areas" and "30 years of experience".
The Kenyan opposition has already described the bill – which will facilitate government wiretapping and allow terror suspects to be detained for up to a year without charge – as "draconian."
New anti-terrorism law allows for longer detention of suspects and penalties for media printing material that is "likely to cause fear or alarm".
Kenyatta used the occasion to reflect on a string of terrorist attacks in the country that had left more than 300 people dead since last year
Kenyatta had been accused of committing crimes against humanity after allegedly inciting the post-election violence, during which more than 1,000 people were killed.
The International Criminal Court's prosecutor has withdrawn charges of crimes against humanity directed at Kenyan President Uhuru Kenyatta