Phillip Margolin was born in New York City in 1944. After receiving a B.A. in Government in 1965, he worked as a Peace Corps volunteer in Liberia until 1967. He graduated from the New York University School of Law in 1970, and has worked for 25 years as a criminal defense attorney, an occupation of choice inspired by the Perry Mason books. He started to work in 1970 at the Oregon Court of Appeals.

He published his first story, The Girl in the Yellow Bikini, in 1974, and became a full-time writer in 1996. He has written 12 books as of January 2007. He lists as his favourite writer Joseph Conrad, and among his favourite books War and Peace by Leo Tolstoy and Stone City by Mitchell Smith.

Philip Margolin was married to Doreen Stamm in 1968. They had two children, Ami and Daniel. Doreen, also a defense attorney, died from cancer in January 2007.

Phillip Margolin is also the president of "Chess for Success", a non-profit organisation aimed at children to help them by learning chess.