Blair has starred in several television films, including Born Innocent (1974), Sarah T. – Portrait of a Teenage Alcoholic (1975), and Stranger in Our House (1978).

[5] When Blair was two years old, her father, a Navy test pilot-turned-executive recruiter, took a job in New York City, and the family relocated to Westport, Connecticut.

[7] Linda worked as a child model at age five,[8] appearing in Sears, J.C. Penney and Macy's catalogues, and in over 70 commercials for Welch's grape jams and various other companies.

[9] In 1972, Blair was selected from a field of 600 applicants for her most notable role as Regan, the possessed daughter of a famous actress, in William Friedkin's The Exorcist (1973).

[8] Film critic and historian Mark Clark notes that in her performance, "Blair matches [adult co-star] Ellen Burstyn note-for-note.

[3] To combat the rumors and media speculation surrounding her, Warner Bros. sent the then-14-year-old Blair on an international press tour in hopes of demonstrating that she was "just a normal teenager".

[3] Blair starred opposite Kim Hunter in the controversial television film Born Innocent (1974),[11] in which she plays a runaway teenager who is sexually abused.

[14] A steady series of job offers led Blair to relocate to Los Angeles in 1975, where she lived with her older sister, Debbie.

[3] Between 1975 and 1978, she had lead roles in numerous television films: Sarah T. – Portrait of a Teenage Alcoholic (1975), as a teenager who becomes addicted to alcohol;[12] Sweet Hostage (1975) opposite Martin Sheen, in which she plays a kidnapping victim;[12] and Victory at Entebbe (1976), a dramatization of a real-life hostage situation starring Anthony Hopkins and Elizabeth Taylor.

[16] After filming Exorcist II: The Heretic, Blair took a year off from acting and competed in national equestrian circuits under the pseudonym Martha McDonald.

[5] In 1978, she made a return to acting in the Wes Craven-directed television horror film Stranger in Our House (retitled Summer of Fear), based on the novel by Lois Duncan,[17] and also with the lead role in the Canadian production Wild Horse Hank, in which she used her equestrian skills to play a college student saving wild horses from ranchers.

[19] The following year, she co-starred with Dirk Benedict in Ruckus, playing a young woman who helps a maligned Vietnam veteran evade antagonistic locals in a small town.

She starred opposite Peter Barton and Vincent Van Patten in the slasher film Hell Night (1981), followed by roles in the women-in-prison film Chained Heat (1983), playing a teenager in a women's prison,[21] and the exploitation thriller Savage Streets (1984), in which she plays the lead of a female vigilante street gang who targets male rapists.

[23] This was followed by a lead in the direct-to-video film Night Force (1985), in which Blair portrayed a woman who travels to Mexico to save her friend from terrorists.

[17] The following year, she starred in the romantic comedy Up Your Alley opposite Murray Langston,[27] and the Exorcist spoof Repossessed in 1990, co-starring Leslie Nielsen.

[28] In 1996, Blair reunited with director Wes Craven for a cameo role as a reporter in Scream (1996),[17] In 1997 she starred in a Broadway revival of Grease, playing Rizzo.

In 2000, she was cast as a regular in the BBC television show, L.A. 7, and between 2001 and 2003, hosted Fox Family's Scariest Places on Earth, a reality series profiling reportedly haunted locations throughout the world.

In 2006, she guest-starred on The CW television series Supernatural, playing the part of Detective Diana Ballard, as she aids Sam and Dean Winchester in the episode "The Usual Suspects", which aired November 9, 2006.

[37] In 2013, Blair accepted a role in the comedy web series Whoa!, and has since appeared in the 2016 feature The Green Fairy, and the films Surge of Power: Revenge of the Sequel (2016) and the upcoming Landfill (post-production).

[3][5] She also dated Deep Purple and Trapeze bassist Glenn Hughes, and Neil Giraldo, guitarist and future husband of Pat Benatar.