Who narrated the Mahabharata to King Janamejaya?

Vaishampayana, also spelled Vaisampayana, narrated the Mahabharata to King Janamejaya. The recitation took place during Janamejaya’s sarpa satra, or snake sacrifice, traditionally located at Takshashila.

Vaishampayana was one of Vyasa’s principal disciples. According to the epic’s traditional transmission story, Vyasa taught him the Mahabharata, and Vaishampayana then recited it to Janamejaya when the king asked about his ancestors and the history of the Kuru dynasty.

Janamejaya was the son of Parikshit, grandson of Abhimanyu, and great-grandson of Arjuna. His snake sacrifice was organized in an attempt to destroy the serpent race after the snake king Takshaka caused Parikshit’s death. The epic’s narration is therefore embedded in a dramatic ritual setting rather than presented as a detached historical chronicle.

A common mix-up is Vyasa, who is traditionally regarded as the composer or source of the epic, and Ugrashrava Sauti, who later retold it to sages at Naimisha Forest. For the specific question about the narration to Janamejaya, Vaishampayana is the canonical answer.