Dexter was born in Pontiac, Michigan. After his father died, when Dexter was four, he and his mother moved to Milledgeville, Georgia, where she married a college physics professor.

He was a columnist for the Philadelphia Daily News, The Sacramento Bee, and syndicated to many newspapers such as the Seattle Post-Intelligencer.

Prior to that he worked for what is now The Palm Beach Post in West Palm Beach, Florida, but quit in 1972 because the paper's owners forced the editorial page editor to endorse Richard Nixon over George McGovern.

He began writing fiction after a life-changing 1981 incident in which thirty drunken Philadelphians in the neighborhood of Grays Ferry, armed with baseball bats and upset by a recent column about a drug deal-gone-wrong murder, beat the writer severely. The brother of the homicide victim was a bartender at a Grays Ferry bar and Dexter and his friend Randall "Tex" Cobb went to the bar to talk to him because the family had called the newspaper to complain. In the fight that occurred outside the bar in the street, Cobb received a broken arm that helped end his professional boxing career, and Dexter was hospitalized with a several injuries, including a broken back, pelvic bone, brain damage, and dental devastation.

Dexter lives and writes on Whidbey Island in the Puget Sound area of the state of Washington.

Paper Trails, published in 2007, is a compilation of columns he wrote for the Philadelphia Daily News and The Sacramento Bee from the 1970s to the 1990s.

Novels

• God's Pocket (1983)
• Deadwood (1986)
• Paris Trout (1988) (1988 National Book Award for Fiction)
• Brotherly Love (1991)
• The Paperboy (1995) (1996 Literary Award, PEN Center USA)
• Train (2003)
• Spooner (2009)

Nonfiction

• Paper Trails (2007)

Screenplays

• Paris Trout (1991)
• Rush (1991)
• Michael (1996)
• Mulholland Falls (1996)