Nampillai was born Varadar, and is often called Nambur Varadar after his family's village. He was devoted to Thirumangai Alwar, and so was also called Kalivairi Dasar. He came to Nanjeeyar to learn, and when, as the tradition tells, he lost Nanjeeyar's manuscript in the Kaveri and wrote it out again with deeper meanings, Nanjeeyar joyfully called him Nam Pillai, "our own son".
After Nanjeeyar, Nampillai became the acharya of Srirangam. Every day he explained Thiruvaymozhi to large gatherings, so warmly and so clearly that people came from everywhere to listen. According to tradition, Namperumal Himself once rose to look at the crowd gathered for Nampillai's lecture, and a temple servant gently reminded the Lord to stay as He was in His archa form.
The tradition also remembers his humility. A senior Sri Vaishnava, Kandadai Thozhappar, once spoke harshly of him in front of Perumal. That night, ashamed, he set out to apologise — and found Nampillai already waiting at his door, to ask pardon for having caused him displeasure. Moved, Thozhappar called him Lokacharyar, "the teacher of the world", and the name stayed with him.
Nampillai's lectures on Thiruvaymozhi were written down by his disciple Vadakku Thiruveedhi Pillai. Known as the Eedu, or the Thirty-Six Thousand Padi, they remain the heart of the sampradaya's understanding of Swami Nammalwar's words.