He was born in the village Botale. He was the son of Mudaliyar Don Spater Senanayake and Dona Catherina Elizabeth Perera Gunasekera Senanayake. Brought up in a Buddhist family, he entered Anglican school S. Thomas' College, Mutwal. Though a smart student, at school Senanayake did not succeed. He witnessed Buck’s famous farewell speech "You have learned the best lessons from STC (St. Thomas’s College)... true manliness and truth, courage, purity and all those things that make a man a gentleman...".