The son of a rabbi, Segal attended Midwood High School in Brooklyn and traveled to Switzerland to take summer courses. He attended Harvard College, graduating as both the class poet and Latin salutatorian in 1958, after which he obtained his master's degree (in 1959) and a doctorate (in 1965) in comparative literature from Harvard University.
In the late 1960s, Segal collaborated on other screenplays, and also had written a synthetic romantic story by himself about a Harvard and a Radcliffe student, but failed to sell it. However, literary agent Lois Wallace at the William Morris Agency suggested he turn the script into a novel and the result was a literary and motion picture phenomenon called Love Story. A New York Times No. 1 bestseller, the book became the top selling work of fiction for all of 1970 in the United States, and was translated into 33 languages worldwide. The motion picture of the same name was the number one box office attraction of 1971.
Erich Segal went on to write more novels and screenplays, including the 1977 sequel to Love Story, called Oliver's Story.
He has published a number of scholarly works as well as teaching at the university level. He has acted as a visiting professor for the University of Munich, Princeton University, and Dartmouth College. He has written widely on Greek and Latin literature. His novel The Class (1985), a saga based on the Harvard Class of 1958, was also a bestseller, and won literary honour in France and Italy. Doctors was another New York Times bestseller from Segal.
Segal has been married to Karen Marianne James since 1975; they have two daughters.