 Wimalasena contested the 1965 parliamentary elections and was successful in gaining the seat of Senkadagala, defeating the sitting member, Ranaraja.Wimalasena served as the Parliamentary Secretary to the Minister of Finance between 1965 and 1970 in the Third Dudley Senanayake cabinet and between 1966 and 1970 was the Governor of the Asian Development Bank (Sri Lanka).He retained the seat in the subsequent 1970 election with over 50% of the vote however chose not to run in the 1977 election.