Uhuru Kenyatta, the son of Kenya's founding leader, narrowly edged out his main rival to win the Kenyan elections with 50.07% of the vote, the election commission announced Saturday.
Prime Minister Raila Odinga received 43.31% of the vote, and said he will challenge the count.
According to the constitution, 50% plus one vote is required for an outright win.
"We celebrate the triumph of democracy; the triumph of peace; the triumph of nationhood," Kenyatta said. "Despite the misgivings of many in the world, we demonstrated a level of political maturity that surpassed expectations."
Kenyatta is currently facing charges at the International Criminal Court over post-election violence that plunged the nation into chaos in 2007.