Since her parents did not approve of her dropping out of law school, she needed a source of income to pay her college fees. In 1994, she started in porn by answering an advertisement for a modeling agency in LA Weekly. The "agency" turned out to be an adult film company, which led to photo shoots and then an interview with porn Director John T. Bone. Bone, recognizing Chong's talent, embarked on producing a series of films starring her. She was the new hardcore star in her early gang bangs, such as Sgt. Pecker's Lonely Hearts Club Gangbang and I Can't Believe I Did the Whole Team. Chong was reportedly interested in blurring the boundary between pornography and performance art in her work.

The production that propelled her into the limelight was another Bone production, The World's Biggest Gang Bang. Chong took part in this gang bang on January 19, 1995, when she was 22 years old. She said part of her motivation to do the film was a Desire to challenge gender roles. She appeared in advertisements on adult television to solicit 300 participants for the event. Initial reports differed as to whether she had sex with 251 men over the course of 10 hours, or with around 70 men multiple times to reach a total of 251—the largest number ever in a pornographic film. Acting on the understanding that male participants who had verified a recent negative test for HIV would wear a color-coded tag, Chong had sex with some men without a condom. It later emerged that the testing had not been as strictly verified as the producers had led Chong to believe. Even though the movie became one of the highest-grossing pornographic films of all time, Chong was never paid the US$10,000 she was promised, and she apparently never received any money at all from the video.

The sensation caught the interest of university film student Gough Lewis. He met Chong and set out to produce a documentary about her. The film, Sex: The Annabel Chong Story, was released in 1999. It includes footage from the gang bang shooting and her subsequent publicity appearances, explores Chong's motives, revisits with her the site of her rape and depicts a painful conversation in Singapore between Chong and her mother, who had not known about her daughter's porn career before then. It was directed by Lewis and featured contributions from Chong, Al Goldstein, Ron Jeremy and Seymore Butts. In the film, Chong stated that she intended the World's Biggest Gang Bang to challenge "the notion of women as passive sex objects," and added, "We're not wilting violets, we're not victims, for Christ's sake. Female sexuality is as aggressive as male sexuality. I wanted to take on the role of the stud. The more [partners], the better." She also self-harmed in the film, taking a knife to her arm. The documentary propelled Chong further into the world media as it became a hit at the 1999 Sundance Film Festival, where it was nominated for a Grand Jury Prize.

Chong continued to work in the adult industry for a short while after the documentary came out, directing and starring in movies as well as setting up a website. In 2000 she directed and performed in the gang bang movie Pornomancer, her take on william Gibson's novel Neuromancer. After 2000 she largely stopped appearing in mainstream adult videos, concentrating instead on producing content for her website and appearing in a few BDSM videos. In 2003 she completely retired from porn, thanking her fans in a final message on her website that announced, "Annabel is dead and is now replaced full time by her Evil Doppelganger, who is incredibly bored with the entire concept of Annabel and would prefer to do something different for a change." She stated that she intended to "begin her new life of peace and relative obscurity." She stopped discussing her former career in the adult industry after her retirement. In limited correspondence for the biographical play 251, she told the producers, "Do whatever you want with Annabel Chong because this person doesn't exist anymore."

The event also prompted author Chuck Palahniuk to write a novel, Snuff, about a fictional character who aimed to surpass Chong's record by having sex with 600 men. In 2007 a play written by Ng Yi-Sheng based on her story, 251, was staged in Singapore, directed by Loretta Chen.

As of 2008, she was working as a web developer in California. In 2011 Complex magazine ranked her at #41 in their list of “The Top 50 Hottest Asian Porn Stars of All Time.”