The military will be sent to four counties in northern Kenya following weeks of clashes among rival local people.
MPs approved a decision by President Kenyatta to send in the troops after it was presented for debate on Thursday night.
The MPs endorsed the deployment of troops in Marsabit, Samburu, West Pokot and Turkana.
The debate lasted 15 minutes on the last day of Parliament sittings this year.
President Kenyatta’s request was communicated to the House by Speaker Justin Muturi at 9.40pm as MPs rushed to finish pending business before the break.
“This request is necessitated by the fact that in the recent past, there has been inter-clan conflict led by militias with sophisticated weapons in the county of Marsabit,” Majority Leader Aden Duale told the House.
He said some of the militia in Marsabit were from a neighbouring county and military intervention was critical to avert further killings and destruction of property.
The government needs to send two infantry companies — up to 230 soldiers — and planes.
Mr Duale said the KDF was needed “for such a period until the security situation is restored and stabilised.”
The motion was seconded by Justice and Legal Affairs Committee chairman Samuel Chepkong’a.
Mr Chepkong’a said he had learnt from Turkana and Pokot colleagues that some of the militia who had held a village in Lorogon hostage were foreigners.
Interior Cabinet Secretary Joseph Ole Lenku said Kenya Defence Forces would help the police to restore order because they were better equipped to confront the warring groups.
He also said all police officers on leave had been ordered to return to work to boost security in other parts of Kenya during the festive season.
“We are confident that security will be restored in all the trouble spots,” he said.
Mr Lenku said security officers at the Coast were also on high alert following reports that some religious leaders were urging youth to cause unrest. “We will not tolerate such religious leaders. We are putting them on notice. Preaching hatred and violence cannot be part of any religious doctrine,” he said at his Harambee House office.
He said next week he would lead a delegation to Turkana, Pokot, Samburu, Moyale and Mombasa for meetings with residents to talk peace. “For the warmongers, there is only one place, behind bars,” warned the Cabinet Secretary.
Police investigations have revealed that some politicians in those regions were bankrolling the conflicts.
“The residents there are not capable of staging such attacks. They are poor. Somebody is financing them. It’s the financiers we are after,” he said.
On Tuesday, the wife of a chief was killed while two police officers and a reservist were injured by bandits at the Samburu village of Lomero.
This is the first time the Executive has asked the Legislature for the permission to deploy the Defence Forces for internal security duties.