Wijetunga was born on 15 February 1916 to Wijethunga Mudiyanselage Delgahapitiya Arachchila and his wife Manamperi Mudiyanselage Palingumanike Manamperi, as the eldest child in a middle-class Kandyan Govigama Sinhala Buddhist family living on the outskirts of the then Udunuwara parliamentary seat in the Kandy District of the Central Province in Sri Lanka.

After completing his schooling, he joined Ceylon Police as a constable in 1939 and served in Borella, Fort and Maradana and left service in 1942.

He lost the Udunuwara electorate in 1970, but was returned to Parliament in the 1977 UNP landslide, being appointed Cabinet Minister of Information and Broadcasting in the J.R. Jayewardene administration.

During this regime, Wijetunga functioned in various ministerial capacities holding the portfolios of Posts and Telecommunication, Power, Highways and Agricultural Development.

He also held the Ministries of Finance and Labour and Vocational Training in addition to being the State Minister of Defence in the Premadasa administration.

A week later President Premadasa was also murdered in Colombo on May Day 1993 in a suicide bombing widely considered to be an act of the Tamil Tigers.

Even though under the constitution, Wijetunga was bestowed with wide powers, he chose not to exercise much authority, letting the Prime Minister manage the affairs of the country.