On-screen, he is known for his recurring role as Andy Baker on the Netflix series 13 Reasons Why, Officer Krupke in West Side Story, and reporter Matt Carroll in Spotlight.

[2] His uncle, Brian Kelly, was an actor featured in the series Flipper and a producer of the movie Blade Runner.

He received a nomination for the Tony Award for Best Featured Actor in a Musical in 2002 for his portrayal of Sidney Falco in Sweet Smell of Success, co-starring John Lithgow.

James's additional Broadway credits include Titanic (Frederick Barrett), Lincoln Center's Carousel, and Blood Brothers.

His Off-Broadway credits include Andrew Lippa's The Wild Party in 2000 opposite Julia Murney and Idina Menzel, for which he received a Drama Desk Award nomination, as well as Adam Guettel's Floyd Collins and the Gershwins' Pardon My English.

He appeared in Martin McDonagh's The Lieutenant of Inishmore on Broadway, replaced Norbert Leo Butz in Dirty Rotten Scoundrels, and starred in The Apple Tree opposite Kristin Chenoweth.

[5][6] He then starred opposite Daniel Breaker, Sutton Foster, and Christopher Sieber as the titular character in Shrek The Musical.

[32] He starred as the original King George III in the Off-Broadway production of the musical Hamilton, with previews starting January 20, 2015, and officially opening on February 17.

[33] He starred in the Broadway musical Something Rotten!, which opened in previews at the St. James Theatre on March 23, 2015, and officially on April 22,[34] for which he received his third Tony nomination.

[36] He reprised his role as King George III in the Broadway production of Hamilton for a limited engagement that began on April 13, 2017, and continued through July 16, 2017.

[37][38] In 2017, James played Andy Baker in the Netflix drama series 13 Reasons Why,[39] a role he later reprised in the second season of the show in 2018.

[42] James starred in the Broadway play The Ferryman at the Bernard B. Jacobs Theatre as Quinn Carney beginning on February 19, 2019, replacing Paddy Considine, who originated the role.

[49] James originated the role of Joe Clay in the premiere production of Days of Wine and Roses at the Off-Broadway Linda Gross Theater in summer 2023.