As an actor, Reiner first came to national prominence with the role of Mike "Meathead" Stivic on the CBS sitcom All in the Family (1971–1979), a performance that earned him two Primetime Emmy Awards.

[1] His other acting credits include Throw Momma from the Train (1987), Sleepless in Seattle (1993), Bullets Over Broadway (1994), The First Wives Club (1996), Primary Colors (1998), EDtv (1999), Everyone's Hero (2006), and The Wolf of Wall Street (2013).

Two years later, Reiner became famous playing Michael Stivic, Archie Bunker's liberal son-in-law, on Norman Lear's 1970s situation comedy All in the Family, which was inspired by the British sitcom Till Death Us Do Part.

The character's nickname "Meathead" (given to him by his cantankerous father-in-law Archie) became closely associated with him, even after he had left the role and went on to build a career as a director.

Starring Richard S. Castellano, the show depicted the life of the harried Italian American superintendent of a New York City apartment building and ran for 10 episodes in the summer of 1972.

These include the romantic comedy When Harry Met Sally... (1989), which has been critically ranked among the all-time best of its genre,[8] the tense thriller Misery (1990), for which Kathy Bates won the Academy Award for Best Actress, and his most commercially successful work, the military courtroom drama A Few Good Men (1992), which was nominated for the Academy Award for Best Picture.

[9] Subsequent films directed by Reiner include the political romance The American President (1995), the courtroom drama Ghosts of Mississippi (1996), and the uplifting comedy The Bucket List (2007).

Reiner has continued to act in supporting roles in a number of films and television shows, including Throw Momma from the Train (1987), Sleepless in Seattle (1993), Bullets Over Broadway (1994), The First Wives Club (1996), Primary Colors (1998), EDtv (1999), New Girl (2012–2018), and The Wolf of Wall Street (2013).

[11] Reiner is a co-founder of the American Foundation for Equal Rights, which initiated the court challenge against California Proposition 8 that banned same-sex marriage in the state.

His lobbying, particularly as an anti-smoking advocate, prompted his likeness to be used in a satirical role in a South Park episode titled "Butt Out", in which he is depicted as a morbidly obese, hypocritical tyrant.

[13][14] Reiner came under criticism for campaigning for a ballot measure (Prop 82) to fund state-run preschools while still chair of the First Five Commission, causing him to resign from his position on March 29, 2006.

He is also active in environmental issues, and he successfully led the effort to establish California's Ahmanson Ranch as a state park and wildlife refuge rather than as a commercial real estate development.

[17][18] He and David Frum launched the site in September 2017 with Morgan Freeman warning people that "We are at war" and that Russia has attacked the United States.

[18] Others on the committee's advisory board at the time of launch included James Clapper, Max Boot, Charles Sykes, and Norman Ornstein.