Nazarbayev had said last week he would fire billionaire Timur Kulibayev, one of the nation's richest and most influential people, after the Dec. 16-17 riots in the west of the country killed at least 16 people and wounded more than 100.
The bloodshed, which occurred on Independence Day, dealt a serious blow to the image of stability that Nazarbayev has touted as his main achievement in the vast nation of 16.6 million, Central Asia's largest economy and oil producer.
Deputy Prime Minister Umirzak Shukeyev was appointed to run Samruk-Kazyna, which manages state assets worth around $80 billion, Prime Minister Karim Masimov said.
Nazarbayev, a 71-year-old former steelworker who has put market reforms in place and overseen massive foreign direct investment but brooks no dissent, is under international pressure to investigate the unprecedented violence.
The clashes in the Mangistau region were centred on the town of Zhanaozen, 150 km (95 miles) from the Caspian Sea.
People in overalls bearing oil company logos were among those on the main square when protesters and riot police clashed on Dec. 16. Police fired shots and buildings were torched, including the local oil company headquarters.
Thousands of workers had been on strike since May, demanding higher wages and protesting at what they saw as illegal sackings of their colleagues.
Firing Kulibayev, who is married to Nazarbayev's middle daughter Dinara, is a signal that the veteran leader is not ready to relinquish his grip on power, analysts say.
Investors were waiting to see whether Kulibayev would be sidelined as a potential candidate to succeed his father-in-law.