He had served as a lecturer in Mass Communication at the Kelaniya University Mass Communication Faculty from 1982 and later obtained his Moscow State University Ph.D in Philosophy.
He has authored several books on mass communication, among them Sannivedana Vimarshana (Exploring Communication) and Pattara Sihiwatana Satahan ( Down Memory Lane with Newspapers). He had been Editor of a number of magazines and journals.
Dr Piyadasa has directed several documentary films including Pattara Mahagedara, Balagenweema (Empowerment) and Andurata Eliyak ( Light to Dark ).
He worked as a Director of Sri Lanka Broadcasting Corporation from 2001. He was then made a Director of Sri Lanka Rupavahini Corporation.
Dr Piyadasa had been a member of the Press Council.
He was a juror at the 2007 Sarasavi Film Festival and Kelaniya University Kala Sangamaya President from 2009.