He was the Parliamentary Secretary to the Cabinet Minister of State and a Member of Parliament in Sri Lanka.
Born at their family manor house in Nakulugamuwa; he received his secondary education at St Thomas' College, Mt.
Thereafter he qualified as a proctor from the Ceylon Law College and began a legal practice in Tangalle.
He represented the United National Party from the Beliatta electorate in Hambantota district at six general parliamentary elections held between 1947 and 1965.
In the 1965 Dudley Senanayake government, Atapattu was Parliamentary Secretary to the Cabinet Minister of State, J. R. Jayewardene.