After completing his schooling, Amarasekera joined H. W. Cave and Company to study commercial art, then worked at the Survey General's Department as a draughtsman for six years from 1907 and finally joined the staff of the Ceylon Technical College, Maradana as a lecturer in fine arts. Later he founded his own art school, the "Atelier School of Art", which produced many notable artists such as Harry Peiris and Justin Pieris Deraniyagala. He was known for his portraits of the Ceylonese leaders of his time. His works were exhibited at the Royal Academy, the Royal Institute of Painters in Water Colours and the Royal Institute of Oil Painters. In 1919, Amarasekera became the secretary of the Ceylon Society of Arts, its vice-president in 1926 and President in 1959. He was appointed Chairman of the Panel on Painting and Sculpture of Arts Council of Ceylon in 1954. He was an amateur magician with the stage name “Gay Deceiver” and was a founder president of the Association of Ceylon Magicians until his death in 1983. He was responsible for designing the National Art Gallery.
