Rajapaksa entered politics at the age of 34 when he contested the Mulkirigala electorate,[5] representing the People's United Front, at the March 1960 parliamentary elections.

[7] In the subsequent July 1960 General Elections he retained the seat, however this time representing the Sri Lanka Freedom Party, increasing his margin to 68% of the vote.

[8] He was then appointed as the Deputy Minister of Finance in the Sirimavo Bandaranaike cabinet, a position he retained until June 1962,[9] resigning in protest at the government's withdrawal of the subsidy on rice.

[5][12] Following his death in 1976, his older brother Lakshman, selected as the SLFP candidate, was successful in securing the Mulkirigala seat at the subsequent by-election.

[13] His daughter Nirupama is a currently a Member of Parliament[14] for Hambantota and the former Deputy Minister of Tourism and his son Shyamlal (1966-2009) was a former Provincial Councilor and prosecutor for the International Criminal Tribunal for Rwanda.