Barnes has had a varied education, including a secondary education at Los Angeles High School. He continued at Pepperdine University, majoring in Communication Arts. He is a certified hypnotherapist, trained at the Transformative Arts Institute in San Anselmo, California. Barnes is married to Tananarive Due, a writer. The couple live in Los Angeles. Barnes has a daughter from his first marriage and a son from his current marriage.

His true passion, other than writing, is martial and physical arts. He is a Black Belt in Kenpo Karate (Aikka style), and Kodokan Judo. He holds an instructor certificate in Wu Ming Ta, and has an instructor candidate ranking in Filipino Kali stick and knife fighting. He is an advanced student in Jun Fan kickboxing (Bruce Lee method under Dan Inosanto), and is an instructor in Wu Style Tai Chi Chuan under Hawkins Cheung.

He is an intermediate student in self defense pistol shooting (Turnipseed modified Weaver method). He holds a Brown Belt in Shorenji Jiu Jitsu, and intermediate rankings in Tae Kwon Do and Aikido. He completed the Yoga Works basic Hatha Yoga instructor program; is presently studying Pentjak Silat (an Indonesian fighting system) with Guru Stevan Plinck, and Ashtanga Yoga (an aerobic form of yoga).

• The Dream Park series:
• Dream Park (1981) (with Larry Niven)
• The Barsoom Project (1989) (with Larry Niven)
• The California Voodoo Game (1992) (with Larry Niven)

• The Aubry Knight series:
• Street Lethal (1983)
• Gorgon Child (1989)
• Firedance (1993)

• The Heorot series:
• The Legacy of Heorot (1987) (with Larry Niven and Jerry Pournelle)
• Beowulf's Children (1995) (with Larry Niven and Jerry Pournelle)

• The Insh'Allah series:
• Lion's Blood (2002) (winner 2003 Endeavour Award)
• Zulu Heart (2003)

• Stand-alone novels, screenplays, and other works:
• Casanegra (with Blair Underwood and Tananarive Due)
• The Descent of Anansi (1982) (with Larry Niven)
• The Kundalini Equation (1986)
• Fusion (1987) (issues #1-5 only)
• Achilles' Choice (1991) (with Larry Niven)
• Blood Brothers (1996)
• Iron Shadows (1997)
• Far Beyond the Stars (1998) (Deep Space Nine novelization)
• The Lives of Dax: "The Music Between the Notes" (1999)
• Saturn's Race (2000) (with Larry Niven)
• Charisma (2002)
• The Cestus Deception (2004) (Star Wars)
• Great Sky Woman (2006)
• "To See the Invisible Man" (a television script adapting a short story by Robert Silverberg, for the 1980s revival of The Twilight Zone)
• Assassin and Other Stories, a collection, ISFiC Press, 2010.
• The Invisible Imam, a novel included in Assassin and Other Stories.