Dinesh Gunawardena, a veteran politician and a close ally of the Rajapaksa family, was appointed on Friday as Sri Lanka's prime minister by President Ranil Wickremesinghe, a day after he was himself sworn in to the top post.
This is the first appointment made by President Wickremesinghe on his first day in office.
A stalwart of Sri Lankan politics, Gunawardena, 73, earlier served as the foreign minister and education minister.
He was appointed as home minister in April by then President Gotabaya Rajapaksa.
The prime minister's post fell vacant after Wickremesinghe, 73, was on Thursday sworn in as the country's eighth president after Gotabaya Rajapaksa fled the country and then resigned as president.
A schoolmate of President Wickremesinghe, Gunawardena, has held various cabinet posts in the past.
Born in 1949, Gunawardena is the leader of the Trotskyist majority nationalist Mahajana Eksath Peramuna (MEP) a constituent party of the ruling Sri Lanka Podujana Peramuna (SLPP).
He succeeded his father Philip Gunawardena in 1979 to lead the party after returning from the Netherlands where he completed his higher studies.
His father was a prominent figure in the leftist socialist movement in the British era prior to the country's independence in 1948.
The MEP became the ruling alliance in 1956.
Gunawardena entered parliament for the first time in 1983 from the populous Colombo suburb of Maharagama and became a leading opposition figure until 1994.
He became a Cabinet minister for the first time in 2000. He continued in senior cabinet positions until 2015.
He is a widower and has one son, who is also a member of Parliament.
Gunawardena's appointment came hours after Sri Lankan security forces cleared a protest camp near the presidential palace and made several arrests.
Wickremesinghe, who was on Thursday sworn in as the country's eighth president after he won a parliamentary ballot, earlier said he intends to take legal action against protesters who continue to occupy the President's Office.
The new government faces the task of leading the country out of its economic collapse and restoring order after months of mass protests that forced President Rajapaksa to flee the country and resign.
