Kazakh President Kassym-Jomart Tokayev nominated Alikhan Smailov for prime minister on Tuesday, and the lower house of parliament swiftly voted him in during a session broadcast live on state television.
Smailov, 49, served as first deputy prime minister in the previous cabinet which Tokayev dismissed last week amid violent unrest in the oil-rich Central Asian nation.
Kazakh security forces have detained 9,900 people over the unrest, Kazakhstan's interior ministry said on Tuesday.
The oil-rich former Soviet republic says government buildings were attacked in several major cities after initially peaceful protests against hikes in the price of car fuel turned violent.
Tokayev has said Islamist militants from regional nations and Afghanistan, as well as the Middle East, were among the attackers.
He dismissed his cabinet amid the unrest, along with a number of security officials and detained on suspicion of treason the most senior among them, Karim Masimov, a former head of the national security committee.
Tokayev defended his decision to invite Russian-led troops into the country and said that doubts over the legitimacy of that mission stemmed from a lack of information.
Kazakhstan would soon provide proof to the international community about what had happened, he said. Sixteen members of the security forces were killed, while the number of civilian casualties is still being checked, he said.