He worked as missionary in Elakurichy in Tiruchirapalli during the first six years. Thereafter he served as a parish priest in Kamanayakkanpatti which is one of the oldest mission centres in Tamil Nadu. He also visited several important centres like Tirunelveli, Ramanathaparam, Thanjavur and Madurai in order to learn the Tamil language. He escaped a death sentence. He could not visit the Christian communities as the local kings were hostile. Meanwhile he mastered the Tamil Language.
He adopted an Indian life style and introduced a touch of Hindu aesthetics in the Christian statuary. The churches he built (Poondi Matha Basilica at Poondi near Trichy, Periyanayagi maadha shrine at Konankuppam, and Adaikala maadha shrine at Elakurichi) were architecturally inspired by Hindu temples. These churches have become Catholic pilgrim centres now. He transformed into an Indian ascetic and adopted the saffron coloured dress. He managed to protect Christians against exploitation and persecution. He baptized 12,000 people. He worked in the Thanjavur area till 1738 and settled on the Coromandel Coast in 1740 where he remained till the end of his life. He breathed his last at Ambazhakad in Kerala.
He is considered as one of the classical writers of Tamil literature. He composed literary Tamil grammar. He also composed a grammar for the common use of Tamil which earned him the title of Father of Tamil prose. Several Tamil dictionaries were compiled by him that includes the Chaturakarati, the quadruple lexicon. Thembavani is his greatest poetical work. It is an epic poem that consists of 3615 stanzas. It is regarding the salvation history and the life of Saint Joseph. It is a classic example of Tamil literature. He also wrote a prabandham named Kavalur Kalambagam, a grammatical treatise called Thonnool which is a guide book for catechists with the title Vedhiyar Ozukkam. He also composed Paramarthaguruvin kathai which is a satirical piece on a naive religious teacher and his disciples. He also penned polemical writings against the Lutheran missionaries and didactic religious books which served as an instruction to the Catholics. He also prepared a hand book for newly arrived missionaries.
His Thembavani proves that he had a positive approach to Hinduism. He was one of the best known Jesuits of the 18th century in Tamil Nadu. His statue was erected in 1968 on the Marina beach in Chennai as recognition for his contribution to the Tamil language and literature.