Vendargon was ordained as a priest on 8 December 1934. As vicar for Indians in Negri Sembilan he was responsible for the pastoral care of Roman Catholics working in the rubber plantations. He was transferred to Sungai Petani in Kedah in 1941. After the Japanese invasion of Malaya, all of Vendargon's books and records by Japanese troops. He spent the Japanese occupation years ministering to families in Kedah, Perlis, Kelantan and Trengganu.