James was born in Farmington Hills, Michigan, the son of Edie, an art teacher, and Robert Wolk, a show store owner. His family is Jewish, and James was raised in Reform Judaism. During his teenage years, James worked as an emcee at Bar and Bat Mitzvahs. He graduated from North Farmington High School in 2003, and from the University of Michigan School of Music, Theatre and Dance in 2007.
In 2008, James landed his first television role in Hallmark Hall of Fame's Front of the Class, as Brad Cohen. He subsequently played the title character in the ABC pilot Solving Charlie. In 2010, James was cast as the lead in the Fox television series Lone Star, as Robert Allen, a Texas con man married to the daughter of one of his targets, while simultaneously maintaining a relationship in another town. The show was canceled by Fox after only two episodes.
James played a presidential speechwriter named Andrew Pierce in Georgetown, a 2011 ABC pilot which did not go to air.In Fall 2011, James joined the second season cast of the Showtime dramedy Shameless, with his recurring role of Adam. James played the recurring role of Grant in three episodes of the ABC comedy Happy Endings, beginning with the first intallment on February 8, 2012. In the summer of 2012 James was featured in the USA Network mini-series Political Animals, starring Sigourney Weaver and Ciaran Hinds. James played Douglas Hammond, the good son of a former President of the United States and the current Secretary of State.
In 2013, James joined the season 6 cast of Mad Men, playing mysterious junior account man Bob Benson. As the season progressed, Benson became one of the most talked-about characters on the show. As of the fall of 2013, James appears on the CBS sitcom The Crazy Ones, starring Robin Williams and Sarah Michelle Gellar. James plays a womanizing creative at the Chicago ad agency headed by Williams and Gellar, marking his second role as a worker at an ad agency after Mad Men.
James is on the Board of Directors of the Brad Cohen Tourette Foundations. He also volunteers at Camp Twitch and Shout, which is a camp for children with Tourette syndrome in Georgia.