Hon Premajayantha held various ministerial posts successively before being appointed as Minister of Science, Technology and Research, and facilitated many Japanese development assistance projects coming under his scopes of work. Hon Premajayantha has been the President of the Sri Lanka-Japan Parliamentary Friendship Association from 2005 to 2015. From 2015, he has been the Vice-President up to date. During his tenure, he received many Japanese parliamentary delegations including the one headed by Mr. Koumura, the President of the Japan-Sri Lanka Parliamentary Friendship League in 2014.
A congratulatory message was sent by Mr. Fumio Kishida, Minister for Foreign Affairs of Japan, on 29th April upon the announcement stating “Please accept my sincerest congratulations on the conferment of the Order of the Rising Sun, Gold and Silver Star, in recognition of your outstanding contribution, and my best wishes for your continued good health and happiness”.