He also portrayed Limbo in Planet of the Apes (2001), Eugene Landy in Love & Mercy (2014), and Jerry Heller in Straight Outta Compton (2015).

On television, Giamatti played the title role in the HBO miniseries John Adams (2008), which earned him acclaim and several awards including a Primetime Emmy and Golden Globe.

[3] His mother, Toni Marilyn Giamatti (née Smith), was a homemaker and English teacher who taught at the Hopkins School and had also previously acted.

He performed in numerous theatrical productions, including on Broadway and a stint from 1989 to 1992 with Seattle's Annex Theater,[7] before appearing in some small television and film roles in the early 1990s.

In 1997, Giamatti landed his first high-profile role as Kenny "Pig Vomit" Rushton in the film adaptation of Howard Stern's Private Parts.

Stern praised Giamatti's performance often on his radio program, calling for him to be nominated for the Academy Award for Best Supporting Actor.

Greg Evans of Variety wrote, "[Giamatti,] as the sisters’ pensive, dispirited brother Andrei, plays urban neurosis like a Richard Lewis stand-up routine, then slides into shaky-voiced melodrama when the going gets tough".

In 1999, he played Bob Zmuda and Tony Clifton in Miloš Forman's Andy Kaufman biopic, Man on the Moon.

His portrayal of a depressed writer vacationing in the Santa Barbara wine country garnered him a Golden Globe nomination and an Independent Spirit Award and he was named Best Actor in a Leading Role by several significant film critics groups (New York, Chicago, Toronto, San Francisco, Online Film Critics).

Following the commercial success of Sideways, Giamatti appeared in Cinderella Man, for which he earned an Academy Award nomination for Best Supporting Actor.

In 2006, Giamatti was the lead in M. Night Shyamalan's Lady in the Water, a supernatural thriller, followed by the animated film The Ant Bully, and Neil Burger's drama The Illusionist co-starring Edward Norton.

[14] William Thomas of Empire agreed, adding "The acting, especially from Giamatti as the irascible Adams and Laura Linney as his wife Abigail, who steered him clear of vanity...has the tang of authenticity, even when burdened with great gulps of politicking".

[16] Giamatti received his second Golden Globe[17] win for Best Actor in a Motion Picture - Musical or Comedy for his role in the 2010 film, Barney's Version.

[23] He also had supporting roles in several films, including the animated Turbo and The Congress, as well as Parkland, Saving Mr. Banks, and the critically acclaimed 12 Years a Slave.

[24][25] In addition, Giamatti played the role of New Yorker Harold Levinson, the brother of Cora, the Countess of Grantham (Elizabeth McGovern), in the 2013 Christmas special of the period drama, ITV Studios/Carnival Films television series, Downton Abbey.

[28] From 2016 to 2023, Giamatti played a lead role in the Showtime series Billions, portraying the U.S. Attorney for the Southern District of New York.

Alissa Wilkinson of Vox praised the performances of the two leads, writing "Hahn and Giamatti bring their characteristic warmth-with-an-edge to their characters, and as their relationship unpacks itself onscreen, it feels authentic and lived-in".

[32] That same year he acted in Reed Morano's post-apocalyptic romance drama I Think We're Alone Now and portrayed Samuel Goudsmit in the war film The Catcher Was a Spy.

The film, distributed by Focus Features, received positive reviews, with critics praising Giamatti's performance as a curmudgeonly teacher.

Club[37] among others, Madame Tussauds New York announced that they would host a party in Giamatti's honor to coincide with the premiere of Billions Season 3 on March 25, 2018, at which the founders of the Wax Paul Now movement would speak.

[39] Tussauds announced that if a Change.org petition garnered 500,000 signatures in the nine days leading up to the party, they would agree to create the wax statue of Giamatti.

With these achievements, Giamatti is one of few actors to receive Emmy nominations across all three performance (lead, supporting and guest) and genre (comedy, drama and miniseries or movie) categories.