On 5 November 1963 he was unanimously elected President of the Senate which post he held till his retirement in 1965. In 1956 the Planters Association of Ceylon broke a 102-year-old tradition to elect Senator Thomas Amarasuriya as the first Ceylonese Chairman. He was also the President of the Rotary Club of Colombo and served as the Vice President Buddhist Theosophical Society. He died on 5 May 1979 at the age of 72. He had five daughters and three sons including Hemaka Amarasuriya and Mahendra Amarasuriya. All Ceylon cricket captain Sargo Jayawickrama was his cousin.