In his own words Swofford describes his younger self, before and during his time in the Marine Corps, as "a reader and a loner".

Born into a military family, Swofford was raised living on a military base. His father had served in Vietnam, and before that his grandfather had fought in World War II. In fact, he was conceived in Honolulu while his father was on a 24-hour break from fighting in Vietnam.

Terrified of being a failure in a 'normal' life, Swofford wanted to join the Marines from an early age, as he saw it as "an entry into manhood". However Swofford's father was against his joining, and the first of two recruiters to visit were escorted from the house. Swofford's father had said "I know some things about the military that they don't show you in the brochures".

Swofford joined the Marine Corps at the age of 18, and shortly after he turned 20 he was deployed to Riyadh, Saudi Arabia, awaiting the start of the Gulf War.

He was a Lance Corporal while serving as a Scout Sniper with the Surveillance and Target Acquisition Platoon of 2nd Battalion, 7th Marines, however during his deployment in the Gulf he never fired a shot in anger, despite being fired upon both by the enemy and his own side.

Following the war Swofford was promoted to Corporal and was uncomfortable with the notion that he was a hero, and deliberately missed the homecoming parade near his base. As far as he was concerned, he had simply done his job, and wanted to forget it.

After leaving the Marine Corps following the end of the war in the Gulf, Swofford at first found it difficult to adapt to civilian life. In his own words, it felt "strange to be in a place without having someone telling me to throw my gear in a truck and go somewhere".

Swofford returned to college, doing a variety of jobs to pay his way. His first job upon his return to civilian life was as a bank teller; however, after only a few months he was robbed at gunpoint, which led him to quit. Swofford also found work in warehouses.

While attending the American River College, a community college in Sacramento, Swofford was published in and was the-editor-in-chief of the American River Review, an award-winning literary magazine. Later, he received a Bachelor's degree in English from University of California, Davis and earned a Master of Fine Arts from the Iowa Writers' Workshop, at the University of Iowa.

Swofford committed himself to writing in 1995, at the age of 24, and built on the encouragement he received at college to write Jarhead, which documents his time spent in the Gulf. In the book he portrays a grim view of life as a Marine, and indeed shows himself in a rather unflattering light. He said himself "I could have written a flattering portrait of myself as a young Marine, but it would have been a much lesser book." Reviewing Jarhead for the New York Times, Michiko Kakutani said the book combined "the black humor of Catch-22 with the savagery of Full Metal Jacket and the visceral detail of The Things They Carried."

Following his time at the University of Iowa, and Texas Swofford served as an English professor at Lewis and Clark College, where he taught a class in the school's "Inventing America" program, and St. Mary's College of California until he sold the film rights to Jarhead. Swofford has had articles, both fiction and non-fiction, published in The New York Times, Harper's, Men's Journal, The Iowa Review, and other publications. He is a Michener-Copernicus Fellowship recipient and lives in New York. His first novel, Exit A, was published in January 2007.

Swofford co-produced and narrated the 2006 documentary Semper Fi, is featured in Richard E. Robbins’s documentary Operation Homecoming, and has made appearances on several talk shows and in documentaries.