Wickremanayake was Prime Minister in the Mahinda Rajapaksa Government in 2005. He had earlier held the position of Prime Minister from August 2000 – December 2001, succeeding then Prime Minister Sirimavo Bandaranaike.
Wickremanayake entered politics in 1960 winning the Horana seat in the March General Election as a member of the Mahajana Eksath Peramuna (MEP).
Later in 1970, he was appointed Deputy Minister of Justice and went on to be the General Secretary of the Sri Lanka Freedom Party (SLFP) in 1977.
In the 1994 General Election, he won the Kalutara District seat and was appointed as the Minister of Public Administration, Home Affairs and Plantation Industries and the Leader of the House in President Chandrika Kumaranatunge’s Cabinet. (Colombo Gazette)