Ruck is perhaps best known for his role as Cameron Frye, Ferris Bueller's hypochondriac best friend in John Hughes' Ferris Bueller's Day Off (Ruck was actually 29 when he portrayed the 18-year-old Cameron), and as Stuart Bondek, the lecherous, power-hungry member of the mayor's staff on the hit Abcsitcom Spin City, which ran from 1996-2002.

Ruck played Captain John Harriman of the USS Enterprise-B in the 1994 film, Star Trek Generations, a role which he has reprised along with Generations co-star Walter Koenig and other Trek alumni in the fan film Of Gods and Men. He also played annoying tourist Doug Stephens on the ill-fated bus in the blockbuster Speed. Another supporting role was of the eccentric storm chaser Robert 'Rabbit' Nurick in the 1996 disaster film Twister. His most recent work in film was as a ghost vying for Ricky Gervais' attention in Ghost Town.

Ruck also played Hendry William French in 1990 western film, Young Guns II

In 1990–1991, he starred as Chicago ad man Charlie Davis, in the AbcSeries Going Places. Due to low ratings, Abcpulled the plug and cancelled Going Places after only one season (22 Episodes).

From 1996–2002, he played Stuart Bondek in the sitcom Spin City alongside Michael J. Foxand later, Charlie Sheen

In 2005, he played "Leo Bloom" in the Broadway version of Mel Brooks' The Producers, a role initiated by his Ferris Bueller co-star, Matthew Broderick

He was cast in the pilot of the Tim Minear-created FOX series Drive, but did not appear in the actual series. He also starred in one episode of the Comedy Central sitcom Stella as Richard, a man looking for work. He starred in Episode 9 of the second season of Scrubs as a patient. He played reporter Steve Jacobson on the ESPN miniseries The Bronx is Burning.

In 2006, he guest starred in a single episode of Stargate Atlantis called "The Real World".

In the 2007 comedy Kickin' It Old Skool, he appears as Dr. Frye, a possible reference to Cameron Frye. He even mentions still trying to pay off an old Ferrari, a reference to Cameron totaling his dad's Ferrari in Ferris Bueller's Day Off.

He has a small role in the 2008 M. Night Shyamalan film, The Happening. He currently plays the role of Dean Bowman in the college fraternity drama, Greek. He appeared in a guest role as a manic geologist in an episode of Eureka (TV series).

He plays Mr. Cooverman in the film I Love You, Beth Cooper (film). In 2009 he filmed the medical drama Extraordinary Measures in Portland, Oregon, with star Harrison Ford

He also guest starred as a bank robber in an episode from the third season of the USA Network series Psych and as a lawyer in the fifth season of the Abcseries, Boston Legal.

He recently guest starred as Martin, a magazine reporter, on an episode of Ruby and the Rockits entitled "We Are Family?".

Ruck was born in Cleveland, Ohio. He attended Parma Senior High School located in Parma, Ohio and is a graduate of the University of Illinois.

He married Claudia Stefany in 1984, and had two children with her - a daughter, Emma, and a son, Sam. They divorced in 2005.

He married again, this time to actress Mireille Enos, on January 4, 2008.