Born in Kahawatta, Ratnapura, Seneviratne was the son of Welathanthirige Podi Appuhami and Soma Wijesundara.
This experience helped him in being an active leader of the Sri Lanka Freedom Alliance.
When he first entered mainstream politics in 1977, the Sri Lanka Freedom Alliance was experiencing a severe crisis.
During this crisis situation, Seneviratne acted as the chief organizer of the Palmadulla electorate.
Seneviratne first entered the Parliament of the Democratic Socialist Republic of Sri Lanka in 1989.