His party secured a landslide victory in parliamentary elections that cemented his family’s hold on power, reports AP.
Rajapaksa took oath before his younger brother, President Gotabaya Rajapaksa, at a prominent Buddhist temple on the outskirts of the capital Colombo.
Mahinda Rajapaksa served as the island nation’s president from 2005 to 2015 and is highly popular among the ethnic majority Sinhalese for ending the country’s 25-year civil war against Tamil rebels in 2009.
He was first elected prime minister in 2004 and again appointed for brief periods in 2018 and 2019.
Sri Lanka People’s Front — the party led by the Rajapaksa brothers — won 145 seats in the 225-member Parliament in the election last Wednesday. Its main opponent obtained only 54 seats. A party representing ethnic minority Tamils won 10 seats, and 16 others were split among 12 small parties.
The victory gave the Rajapaksa brothers nearly the two-third majority of seats required to make constitutional changes that could strengthen dynastic rule in the country.
This time, five members of the Rajapaksa family have been elected as lawmakers— Rajapaksa, his son Namal, the eldest brother Chamal and his son Sashindra, and a nephew, Nipuna Ranawaka.
The brothers need 150 seats to be able to change the constitution. At least four small parties collaborate with the Rajapaksas’ party, so they appear to have mustered that support.
However, analysts say any attempt by Gotabaya Rajapaksa to push for changes that will strengthen presidential powers at the expense of the prime minister may trigger sibling rivalry.
Sri Lanka had been ruled by powerful executive presidents since 1978. But a 2015 constitutional amendment strengthened Parliament and the prime minister and put independent commissions in charge of judiciary appointments, police, public services and the conduct of elections.
Gotabaya Rajapaksa was elected president last November after projecting himself as the only leader who could secure the country after the Islamic State-inspired bombings of churches and hotels on Easter Sunday that killed 269 people. Since being elected, he has said he had to work under many restrictions because of the constitutional changes.
However, Mahinda Rajapaksa is unlikely to cede any of his powers that might shrink his influence as he works on promoting his son Namal as heir. Namal and three other members of the family are likely to control key functions in the new administration.
The landslide victory also raises fears of weakening government institutions such as independent commissions.