Harring was born in Los Mochis, Sinaloa, Mexico on March 3, 1964. Her mother, María Elena Martínez-Cairo, is a spiritual Teacher, real estate investor, and former secretary. Her father, Raymond Herring, was a developer and organic farmer of Austrian-German descent. The two divorced in 1971. Harring lived the first ten years of her life in Mexico, before her family relocated to San Antonio, Texas. Harring suffered a head wound from a .45 bullet when she was caught by stray fire from a driveby shooting at age 12. At age 16, she convinced her family to let her study in Switzerland at Aiglon College. She eventually returned to the United States, settling down in El Paso, Texas and entered the world of beauty pageants. She won the title of Miss El Paso USA, and soon after, Miss Texas USA, ultimately going on to win the title of Miss USA 1985. Harring spent the next year traveling through Asia, exploring Europe and working as a social worker in India.

In 1987, she married Count Carl-Eduard von Bismarck-Schönhausen, great-great-grandson of Otto von Bismarck. While she retains the title of Countess von Bismarck-Schönhausen, the couple divorced in 1989.

In 1990, Harring was lead Actress in the Columbia Pictures release The Forbidden Dance, where she played the role of Nisa—a Brazilian Princess who travels to Los Angeles in order to stop a corporation from demolishing her family home. That same year began recurring role on the ABC daytime soap opera General Hospital, as Carla Greco. The next few years she had supporting roles in films like Exit to Eden (1994), and Black Scorpion II: Aftershock (1997). In 1997, she played the role of Paula Stevens in the NBC soap opera Sunset Beach. After leaving the show, she guest-starred on Frasier in the episode “Dial M for Martin”, and appeared in the comedy film Little Nicky.

Harring is most well known for her performance in David Lynch's film Mulholland Drive (2001), opposite Naomi Watts and Justin Theroux. She played both the characters of “Rita” (an amnesiac who names herself after Rita Hayworth when seeing the name on a poster for the movie Gilda) and “Camilla”. In response to her performance and the choice of her for the role, film critic Roger Ebert wrote, “Not many actresses would be bold enough to name themselves after Rita Hayworth, but Harring does, because she can. Slinky and voluptuous in clinging gowns, all she has to do is stand there and she's the first good argument in 55 years for a Gilda remake.” Comparisons were also made between Harring and Ava Gardner by The International Herald Tribune. In 2002 she was awarded the American Latino Media Arts (ALMA) Award for Outstanding Actress in a Feature Film for her performance. Harring went on to work twice more with Lynch—as an anthropomorphic rabbit in the limited series Rabbits (2002) and in a cameo appearance in Inland Empire (2006).

In 2002, she appeared in John Q, and was female lead opposite Jean-Claude Van Damme in Derailed. In 2003, she starred in Mi Casa, Su Casa together with Barbara Eden. In 2004, she was the spoiled wife of antagonist Mr. Saint (John Travolta), Livia Saint in the movie adaptation of Marvel Comics's The Punisher. In 2005, Harring starred in the independent film The King, and later had roles in Nancy Drew, Love in the Time of Cholera, The Caller, and Drool, where she plays an abused wife fleeing her husband.

In 2006, Harring joined the cast of FX's crime drama, The Shield, as defense attorney Rebecca Doyle, appearing in nine episodes of season five. In the role, she is hired by lead character Vic Mackey to protect his team of corrupt police officers against an Internal Affairs investigation. From 2009 to 2010, she also had a recurring role as Evelyn Bass/Elizabeth Fisher in The CW series Gossip Girl. In the show, she plays a woman posing as the long-lost mother of the character Chuck Bass, before her deceit is discovered by the other characters. She has also guest-starred on Law & Order: Special Victims Unit in 2003, Law & Order: Criminal Intent in 2010, and NCIS: Los Angeles in 2012 and 2016. Harring was also cast in the independent film The Loner directed by Daniel Grove, and in 2016 Harring was cast in the English-language remake of the film Inside, as well as Legendary’s first digital film The Thinning, alongside Logan Paul and Peyton List.

Harring studied theatre at the London Academy of Performing Arts, having trained in the Italian Commedia dell'arte, as well as Latin dances, including the Argentine tango. She began her acting career in the film Silent Night, Deadly Night 3: Better Watch Out! Harring played the supporting role of Jerri, a FLIGHT attendant and the girlfriend of one of the protagonists' brother Chris who joins them for family dinner at their Grandmother’s house. In television she portrayed Raúl Juliá's character's wife in the NBC television movie The Alamo: 13 Days to Glory (1987). She was cast by NBC producers after they saw her on the Miss USA broadcast and contacted her with the role.