Jayawardena was commissioned as a
second lieutenant in the
Ceylon Light Infantry, as a
volunteer officer in the
Ceylon Defense Force in 1925. With the onset of
World War II, the Ceylon Light Infantry was expanded for wartime service, and Major Jayawardena was appointed
commanding officer of the 1st Battalion with Captain
Anton Muttukumaru serving as his
adjutant. He was soon promoted to rank of
lieutenant colonel. With the formation of the
Ceylon Army in 1949, he transferred to the
Ceylon Volunteer Force Reserve with the rank of
colonel and was appointed extra
aide-de-camp to the
governor-general in 1950, holding the appointment till 1959. In 1954, he served as
equerry to Her Majesty
Queen Elizabeth II during her Royal visit to Ceylon. He served as the commanding officer of the
Home Guard Regiment when it was formed in 1955. On his retirement from the army in 1959, he was promoted to the
honorary rank of Brigadier, the first volunteer officer to be promoted to the rank. He remained an honorary extra aide-de-camp to the governor-general till the late 1960s. He was the President, Ceylon Rifle Association; the President, Small Bore Rifle Association and the Vice President, British Commonwealth Rifle Club. ==Social service==