Benjamin is a native of Brooklyn, New York, and grew up in the Marine Park neighborhood. He is a collateral descendant of Judah P. Benjamin.

He graduated from Yale University in 1985. At the age of 13, Benjamin broke Bobby Fischer’s record by becoming the youngest-ever U.S. Master; this record was subsequently broken by Stuart Rachels and is presently held by Nicholas Nip. As a junior player he won the National Elementary title in 1976, the National Junior High crown in 1978, and the National High School title 1980-81.

Other successes included the U.S. Junior Championship in 1980. In that same year he earned the IM title. He won the U.S. Junior Championship again in 1982, and the U.S. Open Chess Championship in 1985. He earned the Grandmaster title a year later. Benjamin was the US Chess Champion in 1987(sharing the title with Nick De Firmian), 1997, and 2000. He won Saint John Open I in 1988, and the 2000 Canadian Open Chess Championship. In 1999, he placed first at the QVB Chess Festival in Sydney. He was inducted into the US Chess Hall of Fame in Miami on May 2, 2008. He is the youngest inductee.

He is known for playing offbeat openings such as the Black Knights' Tango and the Pirc, and for winning with only slight edges.

He co-authored Unorthodox Openings along with Eric Schiller, for Batsford publishers in 1987, is a frequent contributor to Chess Life magazine and other chess periodicals, and is a regular commentator on the Internet Chess Club, usually presenting its Game of the Week webcast. He was also the editor-in-chief and founder of the now defunct magazine Chess Chow from 1991-1994. His latest book, is American Grandmaster: Four Decades of Chess Adventures. He is also a frequent contributor to Chess Life Online articles on the USCF website.

Benjamin was hired as the official Grandmaster consultant by IBM to help with the Deep Blue chess computer that defeated World Chess Champion Garry Kasparov in 1997.

Benjamin appeared in the movies Searching for Bobby Fischer and Kasparov and the Machine.

Benjamin beat grandmaster Eduard Gufeld in the U.S. Open in 1998 in Hawaii: 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Qxd4 a6 5.c4 Nf6 6.Nc3 Nc6 7.Qd2 e6 8.Be2 Be7 9.O-O O-O 10.b3 Qa5 11.Bb2 Rd8 12.Rfd1 b5 13.cxb5 axb5 14.a3 Bb7 15.b4 Qb6 16.Qe1 Ba6 17.Qf1 Rab8 18.Rac1 d5 19.exd5 exd5 20.Na4 bxa4 21.Bxa6 Ne4 22.Bd3 Bd6 23.Rc2 Bf4 24.g3 Bh6 25.Re2 f5 26.Qh3 Rf8 27.Bb1 Rbe8 28.Ba2 Ne7 29.Ne5 Qb5 30.Rxe4 fxe4 31.Qe6+ Kh8 32.Qxh6 Nf5 33.Ng6+ Kg8 34.Rxd5 1-0.

Joel Benjamin & Deep Blue Vs Garry Kasparov Match 1997: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 d6 8.c3 O-O 9.h3 h6 10.d4 Re8 11.Nbd2 Bf8 12.Nf1 Bd7 13.Ng3 Na5 14.Bc2 c5 15.b3 Nc6 16.d5 Ne7 17.Be3 Ng6 18.Qd2 Nh7 19.a4 Nh4 20.Nxh4 Qxh4 21.Qe2 Qd8 22.b4 Qc7 23.Rec1 c4 24.Ra3 Rec8 25.Rca1 Qd8 26.f4 Nf6 27.fxe5 dxe5 28.Qf1 Ne8 29.Qf2 Nd6 30.Bb6 Qe8 31.R3a2 Be7 32.Bc5 Bf8 33.Nf5 Bxf5 34.exf5 f6 35.Bxd6 Bxd6 36.axb5 axb5 37.Be4 Rxa2 38.Qxa2 Qd7 39.Qa7 Rc7 40.Qb6 Rb7 41.Ra8+ Kf7 42.Qa6 Qc7 43.Qc6 Qb6+ 44.Kf1 Rb8 45.Ra6 1-0