He has type 2 adult-onset diabetes, and has appeared in related commercials for Liberty Medical.
Brimley was born Anthony Wilford Brimley in Salt Lake City, Utah, on September 27, 1934, where his father worked as a real estate broker. Prior to his career in acting, Brimley dropped out of high school to serve in the United States Marine Corps, where he served in the Aleutian Islands for three years. He also worked as a bodyguard (for Howard Hughes), ranch hand, wrangler and blacksmith. He then began shoeing horses for film and television. He began acting in the 1960s as a riding extra in Westerns and a stunt man at the urging of his friend, actor Robert Duvall.
Brimley married his first wife, the former Lynne Bagley, on July 6, 1956. They had four sons together (James Charles, John Michael, William Carmen and Lawrence Dean) and several grandchildren. Brimley and Lynne were married until her death in June 2000.
Brimley married Beverly Berry on October 31, 2007. Together they have lived in Greybull, Wyoming and Santa Clara, Utah. In 2009, they founded nonprofit organization Hands Across the Saddle (HATS) in the Big Horn Basin.
Brimley's onscreen breakthrough came when he was cast in the popular 1970s television series The Waltons as Walton's Mountain resident Horace Brimley; he made seven appearances between 1974 and 1977.
His first credited feature film performance was in The China Syndrome (1979) as Ted Spindler, a friend and coworker of Jack Lemmon, Jack Godell. Later, Brimley made a brief, but pivotal, appearance in Absence of Malice (1981) as the curmudgeonly, outspoken Assistant U.S. Attorney James A. Wells. He expanded on this cantankerous persona as Pop Fisher, world-weary manager of a slumping baseball team, in The Natural (1984). Shortly thereafter, Brimley secured his first leading role in Ron Howard's Cocoon (1985), portraying Ben Luckett, leader of a group of geriatrics who encounter a magically-reinvigorating swimming pool by their retirement home.
Brimley's close friend Robert Duvall (who also appeared in The Natural) was instrumental in securing for him the role of Harry in Tender Mercies (1983). Duvall, who had not been getting along with director Bruce Beresford, wanted "somebody down here that's on my side, somebody that I can relate to." Beresford felt Brimley was too old for the part, but eventually agreed to the casting. Brimley, like Duvall, clashed with the director; during one instance when Beresford tried to advise Brimley on how Harry would behave, Duvall recalled Brimley responding: "Now look, let me tell you something, I'm Harry. Harry's not over there, Harry's not over here. Until you fire me or get another actor, I'm Harry, and whatever I do is fine 'cause I'm Harry."
Through these and other early roles, Brimley became widely known for portraying gruff or stodgy old men, most notably on the 1980s drama series Our House, also starring Deidre Hall, Chad Allen and Shannen Doherty. However, he made a change from such "good guy" roles when he played William Devasher, ominous head of security for the Bendini, Lambert & Locke law firm, in the Tom Cruise film The Firm (1993) (based on the novel by John Grisham).
After portraying the father of Kevin Kline's protagonist in In & Out (1997), Brimley retreated from Hollywood in favor of involvement in more independent fare. He made an auspicious mainstream comeback with the TNT film Crossfire Trail (2001), co-starring with Tom Selleck (whom he had previously worked with in the '80s film High Road to China). After several more years of independent film and TV acting, Brimley had a supporting role in Did You Hear About The Morgans? (2009), making witty exchanges with star Hugh Grant.
Brimley has frequently appeared in commercials, notably a series of commercials for Quaker Oats Oatmeal throughout the 1980s and 1990s. The Quaker commercials were famous for their slogan: "It's the right thing to do and the tasty way to do it." Brimley is also known for appearing in numerous television advertisements for Liberty Medical, a company specializing in home delivery of medical products such as diabetes testing supplies. He was also the voice-over for a Bryan Foods television commercial campaign, which was created by the New York advertising agency Ally & Gargano, written by A & G group creative director Peter Hoffman, and directed by long-time Hollywood director Howard Zieff.
Brimley has been described as "a fine singer with a warm, rich voice." In 1993, Brimley sang with the Cal State Northridge Jazz Band for a concert benefiting the college's Jazz Endowment Scholarship Fund; in 2004, he released This Time, The Dream's On Me, an album of jazz standards named after the Harold Arlen and Johnny Mercer-penned title track. He is also an accomplished harmonica player; during his 2011 appearance on The Late Late Show with Craig Ferguson, Brimley performed a lively rendition of "Oh! Susanna" much to the delight, and surprise, of Ferguson and the studio audience.
Diagnosed with diabetes in 1979, he began working to raise awareness of the disease. The American Diabetes Association (ADA) honored Brimley in 2008 with an award to recognize his lifetime of service. The ADA presented the award to him at the Port St. Lucie headquarters of Liberty Medical on December 19, 2008. He has visited Veterans Administration hospitals and communities to advise patients on how to manage their diseases.
Brimley has supported advertisements to have Utah allow horse-race gambling. He spoke against the banning of cockfighting in New Mexico on the basis of his support of individual rights. Brimley also spoke at a 1998 Phoenix rally opposing an Arizona ballot proposition to ban cockfighting. Brimley argued that a ban could lead to efforts to restrict use of hunting dogs, which opponents of cockfighting called a distraction from the issue. Brimley enjoys playing poker and has played in the World Series of Poker Main Event. Brimley lent his support to John McCain in the 2008 U.S. presidential election. In the days leading up to his selection for vice president, McCain jokingly stated that he would pick Brimley: "He's a former Marine and great guy and he's older than I am, so that might work."
Brimley has resided in Greybull, Wyoming, and Santa Clara, Utah, since 2006. Brimley is a Mormon.