Jinasada Niyathapala started his political career in 1946 through the
United National Party's Youth movement. In 1949 he held the position of Secretary General in the
United National Party's youth movement. He was an active member of the All Island Youth Movement and from 1949 held the position of Deputy Chairman with Sir
John Kotelawala holding the position of Founding Leader. In 1958 Jinadasa Niyathapala was appointed to the
United National Party Working Committee by
Dudley Senanayake, making him the youngest member of the committee at 29 years old. The same year he was also assigned as
United National Party's chief organiser of the
Kotte electorate. Jinadasa Niyathapala was also the editor-in-chief of
United National Party's official publication Siyarata ().
UNP General Secretary Niyathapala was appointed
General Secretary of
United National Party in 1973 by
J. R. Jayewardene. He also held the position as the Secretary for the Asian region in the World Freedom Movement.
Sri Lanka Freedom Party He left the UNP and contested the
1977 general election from the
Sri Lanka Freedom Party, but lost to
Ananda Tissa de Alwis.
Kotte Municipality Council After rejoining UNP in 1994, Jinadasa Niyathapala was appointed as UNP's chief organiser of
Sri Jayawardenepura Kotte. In 1997 he held the position as the
opposition leader of the
Sri Jayawardenepura Kotte Municipal Council. ==Other political activities==