Neelakandan Pillai (later St. Devasahayam) was born into an affluent Hindu Nair family in Nattalam, Travancore, old Kerala (present-day Kanyakumari District) on 23 April 1712. His father, Vasudevan Namboodiri, who was originally from Kayamkulam (in present-day Kerala state), served as a priest at the Adikesava Perumal Temple in Thiruvattar, Travancore (now in Kanyakumari district of Tamil Nadu). His mother, Devaki Amma, also hailed from Thiruvattar.
According to the matrilineal tradition of that period, Neelakandan was raised not by his father but by his maternal uncle. However, his father personally taught him Sanskrit and Vedanta, ensuring that he received a deep grounding in religious and philosophical studies. This early education shaped his intellectual and spiritual foundation.
The family had considerable influence in the royal palace of Maharaja Marthanda Varma, the ruler of Travancore. As a young man, Neelakandan entered royal service and quickly distinguished himself by his intelligence, discipline, and loyalty. His administrative abilities were recognized, and he was appointed as an official under Ramayyan Dalawa, the Dewan (Prime Minister) of Travancore. In this role, he gained prominence and earned the trust of the royal household.