He served as a member of the Western Provincial Council and was the Sri Lanka Freedom Party chief organiser for the Borella Electorate in Colombo District.
In 1979, when Sumathipala was fifteen, his father died of heart failure, at the age of 55 years, with his mother being solely responsible for managing the family's business activities and raising her children.
In recognition of his expertise, Sumathipala was appointed as a distinguished Professor in Strategic Management by the University of Keiymung in 2014.
Sumathipala was the Colombo District leader of the SLFP, however he had to take a step down when he was appointed as the General Secretary of the UPFA.
[6] Sumathipala entered politics in 2009, when he was elected as a member to the Western Provincial Council and then later to the Sri Lanka Parliament in 2010.
[10] Simultaneously he launched the national newspaper, Lakbima, and a suite of other tabloids including, Sarasi, Rajina, Araliya, Samudura and Sathsara.