In 1991, Campbell played the lead role in The Rocketeer. He went on to appear as “Quincey Morris”, a vampire hunter in Bram Stoker’s Dracula (1992). In 1993, he starred in the short-lived detective series Moon Over Miami, and won the role of Dr. Jon Fielding in the television adaptation of Tales of the City. He appeared in the sequels More Tales of the City in 1998, and Further Tales of the City in 2001.

By the end of filming of 1991’s The Rocketeer, the 31-year-old Campbell was in a romance with 20-year-old co-star Jennifer Connelly. They were involved for five years before they broke up in 1996. He now has a Norwegian wife and child and they live at her family’s farm in Rygge in Norway.

In 1999, Campbell began his role as Rick Sammler on Once and Again, opposite Sela Ward. The series ran for three seasons until 2002, during which time Campbell received a Golden Globe nomination for Best Actor in a Dramatic Series. Campbell then had a regular role as Jordan Collier on the sci-fi series The 4400, which aired for four seasons on the USA Network between 2004–2007. In 2005, he had a recurring role in the teen soap The O.C.

After his role in the 2002 film Enough, in which he played the abusive husband of Jennifer Lopez’s character, he portrayed serial killer Ted Bundy in the 2003 made-for-TV movie The Stranger Beside Me. He then played a college professor accused of raping a student in a 2004 episode of Law & Order: Special Victims Unit, and also played an accused serial killer who defends himself in the 2007 television series Shark. In 2010, Campbell had a recurring role in the short-lived revival of Melrose Place. Following this, Campbell took a prominent role in the AMC series The Killing, an American remake of the Danish series of the same name.

In 2012, Campbell played the stern but kindly father in the independent film, Fat Kid Rules the World. In 2000, Campbell was named one of the “World’s 50 Most Beautiful People” by People magazine. In 2013, he played Abraham Lincoln in the National Geographic television adaptation of the Bill O’Reilly/Martin Dugard book, Killing Lincoln.

From 2017 to 2020, he starred in the Canadian television drama series Cardinal, for which he won the Canadian Screen Award for Best Actor in a Limited Series or Television Film at the 6th Canadian Screen Awards in 2018, the 7th Canadian Screen Awards in 2019 and the 8th Canadian Screen Awards in 2020.