As an actor, Strong is best known for his roles as Jonathan Levinson in Buffy the Vampire Slayer, Doyle McMaster in Gilmore Girls and Danny Siegel in Mad Men.

Strong also is a co-creator, executive producer, director, and writer for the Fox series Empire and created, wrote and directed the award-winning Hulu miniseries Dopesick.

[5][6] Strong attended Mira Costa High School,[7] and then studied film and theatre at the University of Southern California.

[8] Strong is known for playing Jonathan Levinson on the television series Buffy the Vampire Slayer and Paris Geller's boyfriend Doyle McMaster on Gilmore Girls, but he has also appeared in films such as Pleasantville, Dangerous Minds, Seabiscuit, the spoof Shriek If You Know What I Did Last Friday the Thirteenth, and was in the film Sydney White as the Grumpy dork, Gurkin.

Strong has also had guest parts in sitcoms such as Seinfeld, Clueless, 3rd Rock from the Sun, Over the Top, Grey's Anatomy, Boy Meets World and How I Met Your Mother and has also guest-lectured in acting classes on finding a job as an actor.

In the popular AMC series Mad Men he played Danny Siegel, a young man with no talent, trying to break into the advertising industry, later making a career in Hollywood.

[10] At 25, in the hopes of being the lead actor in his own film, Strong wrote a dark comedy about two men who kill an elderly man for his rent-controlled apartment.

[12] The film starred Kevin Spacey, Laura Dern, Denis Leary, John Hurt and Tom Wilkinson and premiered on May 25, 2008.

[16] Strong followed up Recount with the 2012 film adaptation of Game Change, based on the book written by John Heilemann and Mark Halperin.

In December 2013, Strong signed on to pen the new screenplay for the film adaptation of the musical Guys and Dolls, which originally premiered on Broadway in 1950.

[30][31] In October 2021, Strong released Dopesick, a Hulu exclusive miniseries exploring the Sackler family and Purdue Pharma's role in America's opioid crisis.