Jared Francis Harris was born on 24 August 1961 in Hammersmith, London, the second of three sons of the Irish actor Richard Harris (1930–2002) and his first wife, Elizabeth Rees-Williams (1936–2022), a Welsh socialite.^[3] His younger brother is the actor Jamie Harris, his older brother is the director Damian Harris and his maternal grandfather was the politician David Rees-Williams, 1st Baron Ogmore.^[4]

Harris was educated at Ladycross School, a former preparatory boarding independent school in the coastal town of Seaford in East Sussex, as were his brothers Jamie and Damian. He says, "They were famous for discipline, with cold showers every morning", and that "You were never known by your first name there. You were either called by your number, or your last name. Since there were three of us, Damian was 'Harris Ma' for major. I was 'Harris Mi' for minor, and Jamie was 'Harris Minimus,' being the youngest and the smallest".^[5] He then attended Downside School, a Catholic boarding independent school in the village of Stratton-on-the-Fosse (near the market town of Shepton Mallet) in Somerset, in South West England.^[5] He went on to Duke University in North Carolina, United States, graduating in 1984 with a BFA in drama, then returned to England to train as an actor at the Central School of Speech and Drama, graduating in 1989.^[6]

Harris began his film career directing Darkmoor (1983), an unfinished feature-length film for Duke University's Freewater Films. His first film appearance as an actor was in The Rachel Papers (1989). He took minor roles in films such as the western romance Far and Away (1992), the historical epic The Last of the Mohicans (1992), and the crime drama Natural Born Killers (1994). He took the role of Benmont Tench in Jim Jarmusch's Dead Man (1995). He played the aged Will Robinson in the 1998 movie adaptation of the television series Lost in Space. That same year he played Vladimir in the controversial black comedy drama film Happiness (1998), written and directed by Todd Solondz. He played Kenneth Branagh's character's doppelgänger in How to Kill Your Neighbor's Dog (2000).

Other notable roles include Andy Warhol in I Shot Andy Warhol, John Lennon in the television movie Two of Us (2000) and King Henry VIII in the 2003 BBC film adaptation of the novel The Other Boleyn Girl. Harris played Dr. Charles Ashford in Resident Evil: Apocalypse (2004). He played the gruff Captain Anderson in the BBC2 adaptation of To the Ends of the Earth; Mac McGrath in the film Mr. Deeds; Eamon Quinn on the FX series The Riches; and David Robert Jones on Fringe.

He gained fame for his portrayal of Lane Pryce in the AMC period drama series Mad Men from 2009 until 2012. The show focuses on the lives of Ad Men in New York City during the 1960s. He first appeared in season three where he arrives as a British newcomer to Sterling Cooper, and later becomes a partner of the new agency Sterling Cooper Draper Pryce. Paul MacInnes of The Guardian wrote of Lane Pryce, "For much of his three season tenure on the show, Lane has seemed like the archetypal Englishman...He was polite, courteous, dry-witted, stingy. He was also apparently logical and keenly stoic, keeping calm and carrying on when Sterling Cooper broke up and its successor nearly went under."^[7] Harris received critical acclaim for his final appearance in the episode "Commissions and Fees" as well as a nomination for the Primetime Emmy Award for Outstanding Supporting Actor in a Drama Series, losing to Aaron Paul for Breaking Bad in 2012. He returned to the series to direct the 11th episode of season 7, which aired in 2015.

He played Ulysses S. Grant in Steven Spielberg's acclaimed historical drama film Lincoln (2012).^[8]

His portrayal of King George VI in the first series of The Crown was praised by the critic Matt Zoller Seitz, who stated that despite the series' large ensemble, "Harris still manages to communicate the character’s understated sensitivity and awareness of his circumscribed role in England’s drama so poignantly that one can’t help being moved by the performance".^[9] He received nominations for the British Academy Television Award for Best Supporting Actor and the Critics' Choice Television Award for Best Guest Performer in a Drama Series.

He played Captain Francis Crozier in the 2018 series The Terror, based on the Dan Simmons novel of the same name that provided a fictional account of the fate of Franklin's lost expedition. In November 2018, Harris was one of the first recipients of the Royal Canadian Geographical Society's Louie Kamookak Medal, awarded "for making Canada's geography better known to Canadians and to the world", for his portrayal of Captain Crozier. Harris said that he was "gratified" that the series inspired curiosity about the real expedition, remarking, "It’s sort of fitting that history will recall that it was the RCGS that first recognized The Terror, and that we as the recipients walked in the footsteps of Louie Kamookak."^[10]

In 2019, Harris played Valery Legasov in the acclaimed miniseries Chernobyl, which revolves around the Chernobyl disaster of 1986 and the cleanup efforts that followed.^[11] For that role he won the British Academy Television Award for Best Actor and was nominated for the Primetime Emmy Award for Outstanding Lead Actor in a Limited Series or Movie and Golden Globe Award for Best Actor – Miniseries or Television Film. The series was produced by HBO in the United States and Sky UK in the United Kingdom.

In March 2019 Harris joined Jared Leto in Sony's Spider-Man spinoff Morbius.^[12] He plays the developer of psychohistory Hari Seldon in the Foundation television series produced for Apple TV+ which premiered in September 2021.^[13]

In 2024 he played the father of a returning missing child in the British psychological thriller film Reawakening, alongside Erin Doherty and Juliet Stevenson.^[14]. In 2025 he played the Secretary of Defense in Kathryn Bigelow's A House of Dynamite.^[15]

Harris married Jacqueline Goldenberg in 1989 and they divorced three years later.^[16]

Harris married the actress Emilia Fox,^[17] the daughter of the actors Edward Fox and Joanna David, on 16 July 2005. Divorce filings were made in January 2009;^[18] the divorce was finalised in June 2010.

In April 2009 Harris met Allegra Riggios, a lighting designer and television host,^[19] at a comedy club where a mutual friend was performing.^[19][20] They married on 9 November 2013.^[21]

Harris resides in Los Angeles in the United States.^[6]