President Kenyatta and Raila Odinga pledge to end row over 2017 elections as USA secretary of state arrives for talks.
He said they had shown a commitment to working for all Kenyans, regardless of party, to take "the long journey that is necessary to restore the country, eliminate these divisions that are creating obstacles to Kenya's future".
The truce comes months after Kenyans went to two violent elections in the last quarter of 2017.
In their joint address, President Kenyatta referred to Mr Odinga as his "brother".
Last year's fraught election season saw one presidential poll annulled by the courts and the re-run boycotted by the opposition.
Odinga said Kenyans "can not remember why and where they disagreed in the first place".
"These martyrs were butchered by agents of the illegitimate Jubilee administration they were perceived to be "supporters" of Raila Odinga", he said.
The election season blunted growth in Kenya, East Africa's richest economy and a Western ally in a volatile region.
With continued black outs and unstable energy transmission systems, Kenya's President Uhuru Kenyatta has called upon investors to exploit opportunities in power transmission in Kenya.
That's not a coincidence, said independent political analyst Martin Andati. It does not bear the imprint of NASA Summit as it ought to be.
Prominent anti-corruption campaigner John Githongo said it was hard to understand why the meeting happened now and he cautioned that "the devil is in the details".
He said they have agreed to stop any dissent immediately and not to allow the country's diversity to kill their nation.
Madaxweynaha Kenya Uhuru Kenyatta ayaa sheegay in Raila Odinga uu yahay Walaalkii, isla markaana ay billaabayaan geedi socodka ay wada xaajoonayaan halka ay dhibaatada iyo kala qeybsanaanto ka timid.
The Kenyan leader who was sworn in for his second and final term in office on November 28 in 2017 expressed confidence that a healthy collaboration with the opposition will usher in a new era of unity and prosperity.
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With the country at breaking point and growing political and economic injustices reigniting deeply ethnic hatreds, Raila Odinga chose yet again a path he often has: the path of negotiation rather than confrontation to right the wrongs and protects the people from the horrors that this drawn-out, looming conflict posed. "It is good for the country", he said.