Hart is best known for his translations of several Tamil epics into English and for asserting that Tamil should be classified as a classical language, which is stated clearly in a letter addressed to Professor Maraimalai on April 11, 2000. On September 18, 2004 the Indian Union Cabinet recognized Tamil as a classical language. For The Four Hundred Songs of War and Wisdom (1999) Hart, along with co-author Hank Heifetz, was the recipient of the AAS South Asia Council (SAC) Ramanujan Book Prize in 2002. The book is a translation of Purananuru. His book The Poems of The Tamil Anthologies (1979) was nominated for The American Book Award.
Hart is also the author of several Tamil and Sanskrit textbooks. He is married to Kausalya Hart, herself a professor and Tamil textbook author.
In 2015 he was awarded the Padma Shri by the Government of India for his contributions to the study and translation of Indian literature, particularly the Sangam literature of ancient Tamil.