Born in San Francisco, California, Bratt attended Lowell High School, where he developed his dramatic and oratory skills as a member of the Lowell Forensic Society. Bratt went on to earn a B.A. at the University of California, Santa Barbara, and a masters at the American Conservatory Theater, San Francisco, California. His brother Peter Bratt wrote and directed Follow Me Home.

Bratt's best-known role was that of Detective Reynaldo Curtis on the television show Law & Order. The character's mestizo ancestry, a mix of Native Peruvian and German-English backgrounds, was the same as Bratt's. In 1999 and again in 2000, he was nominated for an Emmy Award for Outstanding Supporting Actor in a Drama Series for his work on the series. His more popular films include Miss Congeniality and Traffic.

Bratt dated Julia Roberts for several years. On April 13, 2002, he married actress Talisa Soto, whom he met while filming Piñero. Their first child, daughter Sophia Rosalinda Bratt, was born on December 6, 2002. Their second child, son Mateo Bravery Bratt was born on October 3, 2005 in Los Angeles.