Langenkamp was born in Tulsa, Oklahoma. She graduated from The National Cathedral School for Girls in Washington, D.C. Langenkamp's first acting venture was in her late teens: a small part in Francis Ford Coppola's The Outsiders (1983), filmed to a large extent in her hometown of Tulsa. She then starred in Nickel Mountain (1984). While she was studying at Stanford University, Wes Craven cast her as teen heroine Nancy Thompson in A Nightmare on Elm Street, the first film in the series as he wanted someone very 'non-Hollywood' to play Nancy. He believed that Langenkamp met this quality. For the part she beat out more than 200 actresses. The film follows the story of a group of teenagers who are killed in their dreams one-by-one by a supernatural serial killer. This film rose Langenkamp to prominence and is credited for launching her career.
The film introduced the iconic villain Freddy Krueger, played by Robert Englund. Johnny Depp, in his feature film debut, played Nancy Thompson's boyfriend, Glen Lantz. Veteran film actor John Saxon played Nancy's father, police lieutenant Donald Thompson. The film was both a critical and commercial success, earning a total of $25 million at the American box office. In 1985, she received the Best Actress Award at the Avoriaz Film Festival for this role.
She continued her role as Nancy in A Nightmare on Elm Street 3 (1987), in which she co-starred alongside Patricia Arquette and Laurence Fishburne. John Saxon and Robert Englund also returned with Langenkamp in Dream Warriors.
In between starring roles, she played Marie Lubbock on the television series Just the Ten of Us, which received critical acclaim. It was a spin-off of the popular situation comedy Growing Pains (on which Langenkamp guest-starred), from 1988 to 1990. That same year, she and her castmates were nominated for a Young Artist Award for Best Young Actor/Actress Ensemble in a Television Comedy, Drama Series or Special. She has also made numerous other guest appearances on television. In 1989, she had a cameo role as a victim in Wes Craven's Shocker.
In 1994 Heather starred as herself in the film Wes Craven's New Nightmare alongside Robert Englund. The movie depicted a story in which Freddy Krueger, acknowledged as a fictional movie character, began to break through to the real world to threaten the real life actress who played his nemesis. Many elements of the plot for Wes Craven's New Nightmare are allegedly based on an incident in which Langenkamp was stalked by a fan.
Langenkamp and her husband, David Leroy Anderson, own and operate AFX Studio, a Special F/X Make-Up firm that is credited with the special make-up for such films as Dawn of the Dead, The Cabin in the Woods, Cinderella Man, Dogtown and Z-Boys, Frost/Nixon, Bruce Almighty, Evan Almighty, Dragonfly and Angels and Demons. She also starred in, executive produced, and narrated the 2010 documentary Never Sleep Again: The Elm Street Legacy, which was directed by Daniel Farrands and Andrew Kasch.
Langenkamp also directed a biographical documentary entitled I Am Nancy in 2010.
In 2013, Langenkamp had a supporting role in the film, Star Trek Into Darkness. She is set to star in the upcoming movies, Home and Getting the Kinks Out.