Pillai Lokacharya was born at Srirangam to Vadakku Thiruveedhi Pillai, and was named after his father's acharya, Nampillai. With his younger brother, Azhagiya Manavala Perumal Nayanar, he grew up in the company of the elders and learned all that had come down from Nampillai.
Much of the sampradaya's deepest teaching — on the nature of the soul, the Lord, the goal and the way of surrender — had been passed on by word of mouth, in pieces. Pillai Lokacharya set it out clearly in eighteen works, the Ashtadasa Rahasyams. Mumukshuppadi explains the three rahasyas; Tattva Trayam explains the soul, matter and the Lord; and Srivachana Bhushanam, his crowning work, gathers the heart of the Alwars' and acharyas' words on surrender and on serving the Lord's devotees. He wrote them in simple Manipravalam so that everyone could learn.
The tradition remembers him most for his last years. When, according to tradition in the early fourteenth century, an invading army approached Srirangam, Pillai Lokacharya, already very old, took Namperumal away to safety and travelled south with Him through forests and hills. He left this world on that journey, at Jyotishkudi near Madurai, still in the Lord's service.
Before he passed, he asked that his teaching be given to Thirumalai Azhwar, a learned official at the Madurai court, who would become Thiruvaymozhi Pillai. Through him the teaching reached Manavala Mamunigal.