[2] Gunasekera first contested for a parliamentary seat at the 1st parliamentary election, held between August and September 1947, in the Attangalla electorate, representing the Lanka Sama Samaja Party.
[3] At the 6th parliamentary election, held on 22 March 1965, Gunasekera ran in the Kottawa electorate.
He failed to get elected and was defeated by the United National Party candidate, Mahabalage Don Henry Jayawardena, by 2060 votes.
[4] He was successful in winning the seat at the subsequent 7th parliamentary election, held on 27 May 1970, defeating Jayawardena by 11,495, securing 61% of the total vote.
[5] Prior to the 1977 Sri Lankan parliamentary elections the Kottawa electorate was replaced by the Colombo East Electoral District, Gunasekera contested the seat of Attangalla, where he challenged the sitting member and Prime Minister, Sirimavo Bandaranaike.