He is best known for his motion capture roles comprising motion capture acting, animation and voice work for computer-generated characters such as Gollum in The Lord of the Rings film trilogy (2001–2003) and The Hobbit: An Unexpected Journey (2012), King Kong in the eponymous 2005 film, Caesar in the Planet of the Apes reboot series (2011–2017), Captain Haddock / Sir Francis Haddock in Steven Spielberg's The Adventures of Tintin (2011), Baloo in his self-directed film Mowgli: Legend of the Jungle (2018) and Supreme Leader Snoke in the Star Wars sequel trilogy films The Force Awakens (2015) and The Last Jedi (2017), also portraying Kino Loy in the Star Wars Disney+ series Andor (2022).

He earned a BAFTA and a Golden Globe nomination for his portrayal of serial killer Ian Brady in the British television film Longford (2006) and was nominated for a BAFTA for his portrayal of new wave and punk rock musician Ian Dury in the biopic Sex & Drugs & Rock & Roll (2010).

[7] Serkis portrayed Ulysses Klaue in the Marvel Cinematic Universe (MCU) films Avengers: Age of Ultron (2015) and Black Panther (2018), as well as the Disney+ series What If…?

[17] In his final year at Lancaster he adapted Raymond Briggs's graphic novel The Tin-Pot Foreign General and the Old Iron Woman, a satire about the Falklands War, as a one-man show, which he performed to acclaim.

[18] In his third year at university, Serkis joined the backstage team at the local Duke's Playhouse to earn his Equity card.

Under director Jonathan Petherbridge, who used workshops based on the methods of Augusto Boal, he spent 18 months acting in a broad range of productions from Brecht, Shakespeare and modern British playwrights.

[19] After 16 months, and having gained his Equity card, Serkis joined a series of touring companies, including productions of: Bouncers opposite Hull Truck; Florizel in The Winter's Tale; and the fool in King Lear with director Max Stafford-Clark.

Serkis joined director Mike Leigh's ensemble for two film productions, and appeared in the romantic comedy Loop (1997) alongside Susannah York.

Serkis portrayed Victorian choreographer John D'Auban in Topsy-Turvy, a 1999 film about Gilbert and Sullivan's creation of The Mikado.

[23] Serkis first came to wide public notice for his performance as Sméagol / Gollum, in The Lord of the Rings film trilogy (2001–2003), for which he provided motion-capture movements and voice for the CGI character.

Producer Barrie M. Osborne campaigned for Serkis to have been nominated for the Academy Award for Best Supporting Actor, as his voice, body language and facial expressions were used.

The marketing director of New Line Cinema, Russell Schwartz, had likewise compared Serkis's motion capture presence to John Hurt winning Best Actor while wearing a latex mask in The Elephant Man.

That same year, Serkis appeared in the role of Mr. Grin in Stormbreaker, the film rendition of Anthony Horowitz's Alex Rider novel.

In 2007, he appeared in Sugarhouse, a low-budget independently made film, playing local crime lord Hoodwink, who terrorises an east London housing estate.

[40][41] Serkis played Ulysses Klaue in Marvel Studios' Avengers: Age of Ultron (2015), and was also a motion capture consultant on the film.

[48] In 2022, Serkis returned to the Star Wars franchise in a different, non-CGI role in the Disney+ television series Andor, as Kino Loy.

[49] In October 2024 it was revealed that Serkis would star as Renoir in the upcoming video game Clair Obscur: Expedition 33,[50] set to be released on 24 April 2025.

[52] On 20 October 2012, the studio acquired rights to The Bone Season by Samantha Shannon, and in 2023 was in production with a new motion capture adaptation of George Orwell's Animal Farm.

[57] In May 2024, it was announced that Serkis would direct, executive produce, and star in The Lord of the Rings: The Hunt for Gollum for Warner Bros. Pictures, a working title for a new installment in the Lord of the Rings film series, with Fran Walsh and Philippa Boyens co-writing the screenplay and Jackson co-producing alongside Walsh and Boyens; the film is expected to be released in 2026.

[60] In December 2018, he appeared in a video for People's Vote as UK Prime Minister Theresa May using the voice of Gollum, spoofing May's Brexit deal.

[63] Serkis, together with fellow Lord of the Rings castmates Sean Astin, Sean Bean, Orlando Bloom, Billy Boyd, Ian McKellen, Dominic Monaghan, Viggo Mortensen, Miranda Otto, John Rhys-Davies, Liv Tyler, Karl Urban and Elijah Wood, plus writer Philippa Boyens and director Peter Jackson, on 1 May 2020 joined Josh Gad's YouTube series Reunited Apart, which reunites the cast of popular movies through video-conferencing due to the COVID-19 pandemic, and promotes donations to non-profit charities.

[70] In 2022, Serkis recorded a new audiobook version of the Terry Pratchett Discworld book Small Gods with Bill Nighy and Peter Serafinowicz.

[74] Although Serkis was raised in the Catholic faith of his parents, he has been an atheist since his teenage years,[8] but has stated the culture of Catholicism is still important to him and his family.