The truce comes months after Kenyans went to two violent elections in the last quarter of 2017.
The controversial MP of Parliament who has over the years locked horns with Ruto over a myriad of political issues, declared that he will not mind if President Kenyatta will appoint Odinga to the government.
Mr Miguna said despite Mr Odinga's "betrayal" he will continue fighting for electoral justice.
"We have come to a common understanding, an understanding that this country of Kenya is greater thatn any one individual", Kenyatta tweeted.
The US diplomat, who arrived in Nairobi on Friday, had been due to visit the AIDS-relief programme PEPFAR on Saturday and also attend a ceremony marking 20 years since Al-Qaeda bombed the US embassies in Kenya and Tanzania, killing 224 people.
Kenya was plunged into political crisis after the Supreme Court annulled the August presidential election, due to irregularities, and Odinga and his supporters boycotted a second round in October.
Mr Tillerson assured President Kenyatta that his country was also keen to see continental reforms of the business environment but was glad that the judicial reforms in place meant contracts were respected and there was a clear path on investment.More news: Hockey: England 1 Australia 2
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Mr Odinga said that nothing had been changed before the re-run. "We refuse to allow our diversity to kill our nation", he said.
Kalonzo Musyoka, Musalia Mudavadi and Moses Wetangula have all maintained that they were neither informed nor consulted about the meeting but only came to learn of it on television.
Mr Tillerson was in the Ethiopian capital of Addis Ababa when news of Donald Trump's agreement to meet Mr Kim in unprecedented talks broke late on Thursday.
"The US should not be dismissed or discounted".
That kind of public pressures augurs well for the success of the two leaders' efforts, both of whom made concessions to get the process underway. "They have successfully engineered this", said Aly Khan Satchu, an independent analyst in Nairobi.
He later met with President at State House where he stated the USA was interested in widening its investment in Kenya as well as strengthening the bilateral and trade relations between the two countries. "The Head of State placed the country first and decided that he should sit down with the former Prime Minister and discuss how to move the country forward", said Ngeno.