He entered to politics under the guidance of his great-uncle Don Henry Wijesinghe Kannangara of Thalgaspitiye walawwa.
At the 1st parliamentary election, held on 16 September 1947, Kannangara unsuccessfully contested the Pandura electorate as an independent candidate, receiving only 6,729 votes as opposed to the Bolshevik Samasamaja Party candidate, Henry Peiris, who won with 16,435 votes.
[3][4] Kannangara challenged again for the seat of Pandura at the 2nd parliamentary election held between 24 May 1952 and 30 May 1952 but this time as the United National Party candidate, defeating the incumbent Pieris by 3,856 votes.
[6] Kannangara subsequently contested the Bandaragama electorate at the parliamentary elections in March 1960, which he won by 3,123 votes over his Sri Lanka Freedom Party rival, K. D. David Perera.
[9] He stood for a fourth time at the 1970 parliamentary elections, where he lost to the Sri Lanka Freedom party candidate, Herbert Wickramasinghe, by 11,969 votes.