A graduate of the London Academy of Music and Dramatic Art in 1972, he came to prominence as a character actor for his many roles in film and television.

Notable film roles include Bullets Over Broadway (1994), Topsy-Turvy (1999), Bridget Jones's Diary (2001), Gangs of New York (2002), Another Year (2010), The Iron Lady (2011), Le Week-End (2013), and Brooklyn (2015).

He also acted in blockbuster and studio films such as The Borrowers (1997), Robots (2005), Hot Fuzz (2007), Indiana Jones and the Kingdom of the Crystal Skull (2008), Arthur Christmas (2011), and Cloud Atlas (2012).

[7] Broadbent's early stagework included a number of productions for The National Theatre of Brent as the downtrodden assistant Wallace to Patrick Barlow's self-important actor-manager character Desmond Olivier Dingle.

In 1978, he had two roles, first as Vroomfondel (who may, or may not be, a philosopher) and then as Shooty (a gratuitously violent policeman, who writes novel in crayon) in the Primary Phase of the groundbreaking radio series The Hitchhikers Guide to the Galaxy.

[9] Towards the end of the decade, Broadbent began appearing in small roles on television and films, including a Fielder in The Shout and Mackanees in the Play for Today episode Long Distance Information.

Broadbent ended the decade by taking a leading role in another Mike Leigh film, Topsy-Turvy (1999), playing dramatist Sir William S. Gilbert.

In 2001, Broadbent starred in three of the year's most successful films: Richard Curtis' Bridget Jones's Diary, Baz Luhrmann's Moulin Rouge!

In 2005, Broadbent appeared in the film adaptation of C. S. Lewis' classic children's fantasy novel The Chronicles of Narnia: The Lion, the Witch and the Wardrobe as Professor Kirke.

[11] Based on a true story, the drama tells of Deric Longden's wife, Diana and her fight against a mysterious wasting illness which turned out to be myalgic encephalomyelitis.

Broadbent also appeared in the fourth film in the Indiana Jones series, Indiana Jones and the Kingdom of the Crystal Skull (2008) with Harrison Ford, Shia LaBeouf, Cate Blanchett and Ray Winstone, directed by Steven Spielberg; and in The Young Victoria (2009) alongside Emily Blunt as King William IV.

Broadbent joined a long list of British actors by appearing in Harry Potter and the Half-Blood Prince, as well as the final movie in the series Harry Potter and the Deathly Hallows – Part 2 as Horace Slughorn[12] In 2009, he portrayed Sam Longson, chairman of Derby County football club in the 1960s and 1970s, in the film The Damned United; the starring character in the film was football manager Brian Clough, played by Michael Sheen.

In 2010, he provided the voice for the character Major Mouse in a series of radio advertisements and one produced for television for an energy company, E.ON, for their eonenergyfit.com website campaign.

According to review aggregation website, Rotten Tomatoes, 93% of critics have given the film a positive review, with the critical consensus reading, "Characterized by strong performances and the director's trademark feel for the nuances of everyday life, Another Year marks another solid entry in Mike Leigh's career of kitchen-sink English drama.

That same year he also starred in Cloud Atlas with Tom Hanks, Hugh Grant, Halle Berry, Hugo Weaving, and Ben Whishaw.

[citation needed] In 2015, Broadbent starred in the Oscar nominated film Brooklyn alongside Saoirse Ronan, Domhnall Gleeson and Julie Walters.

Later that year, he also appeared in a role in Alan Bennett's comedy film The Lady in the Van (2015) alongside Maggie Smith and Alex Jennings.

[citation needed] On 28 May 2018, he played Gloucester in the BBC Two production of King Lear acting alongside Anthony Hopkins, Emma Thompson and Florence Pugh.

[20] It was announced that in 2023 he will return to the third instalment of Paddington with again Hugh Bonneville and Julie Walters, and new cast Carla Tous, Antonio Banderas, Olivia Colman and Emily Mortimer.

[24] Broadbent received his Academy Award for Best Supporting Actor for his performance in Richard Eyre's Iris (2001) starring alongside Judi Dench.

Broadbent was offered an OBE in 2002, but he declined it, stating that there were more deserving recipients than actors and that the British Empire was not something he wanted to "celebrate".