Kenya's Supreme Court has upheld William Ruto's presidential election victory.

In a judgment summary read out on Monday on national television, the seven-judge bench dismissed all arguments in the petitions filed Raila Odinga, who finished second in the August 9 elections. The court's action affirmed the Independent Electoral and Boundaries Commission (IEBC) declaration that Ruto won.

"This is a unanimous decision of the court," Chief Justice Martha Koome said as she read out the ruling.

"We declare the election of the first respondent as president-elect to be valid under Article 143 of the Constitution," she said.

Ruto will be sworn in as Kenya's fifth president on September 13, succeeding President Uhuru Kenyatta, who has served his constitutionally mandated two five-year terms.