Kazakhstan President Nursultan Nazarbayev announced his shock resignation on Tuesday, 29 years after taking office.
"I have taken the decision to resign from the post of presidency," the 78-year-old said in a speech broadcast on state television.
Nazarbayev came to power in oil-rich Kazakhstan when it was still a Soviet republic and has previously never indicated a successor.
"The mandate of the presidency will pass to the chairman of the senate for the remainder of my presidential term," Nazarbayev said, referring to the constitution.
The senate chair position is currently held by Nazarbayev loyalist Kassym-Jomart Tokayev, 65, a former prime minister and career diplomat.
Nazarbayev's term expires in March 2020.
The move comes on the back of growing social discontent and an economy still recovering from an oil price plunge in 2014.
Western sanctions against Russia, a key trading partner, have also hit the economy.
The resignation comes just weeks after the ageing strongman dismissed the country's government.
Last month Nazarbayev announced a spending package of several billion dollars on social programmes and state salaries.
He also promised major investments in infrastructure.
Nazarbayev will enjoy significant policy-making powers following his resignation thanks to his constitutional status as "Leader of the Nation".
He became lifelong head of the country's security council last year.
Nazarbayev, who won a 2015 election with almost 98 percent of the vote, was widely expected to seek another term in 2020.