Subramanian was born in Pittsburgh to a Tamil family migrating from India, where his father was a control systems engineer and his mother was a bookkeeper.

[2][3] He earned a Bachelor of Arts from Case Western Reserve University in 2001 and a Juris Doctor from Columbia Law School in 2004.

[4] From 2004 to 2005, Subramanian served as a law clerk to Judge Dennis Jacobs of the United States Court of Appeals for the Second Circuit.

President Biden nominated Subramanian to the seat vacated by Judge Alison Nathan, who was elevated to the United States Court of Appeals for the Second Circuit on March 31, 2022.

[16][17] Subramanian set a trial date for May 5, 2025, alongside issuing an order barring both parties from making statements relating to secret grand jury material and other non-public evidence in the case.