In April 1996 Brown originated the role Carly Corinthos on the American ABC soap opera General Hospital. Brown "quickly became an overnight sensation" and received three Daytime Emmy Awards for her portrayal of Carly. She won for Outstanding Younger Actress in 1997 and 1998, was nominated in 1999, and won again for Outstanding Supporting Actress in 2000. In 2010, she received her first Daytime Emmy nomination in the Lead Actress category for her work as Claudia Zacchara. Brown appeared on the cover of Soap Opera Digest 19 times during her run in the role, and won two Soap Opera Digest Awards in 1998 (Younger Lead Actress) and 2000 (Favorite Actress). She departed the series in April 2001.
After leaving General Hospital, Brown guest-starred on several television series, including Crossing Jordan, Strong Medicine and Without a Trace. She returned to daytime in the role of Julia Morrisey Larrabee on As the World Turns from August 2004 to March 2005, in which she appeared in 109 episodes. In 2004, Brown played the lead role of Kate Vignatti in the fact-based television movie The Perfect Husband: The Laci Peterson Story. She became a regular on the popular CBS crime drama Cold Case in the fall of 2005 but was let go after only a few months (she appeared in five episodes) with the series. In 2006, she starred in her first feature film, the comedy, Big Momma's House 2 and appeared in an episode of Monk the same year. Brown was also seen in the second-season finale of The Closer and on a 2007 episode of the Fox police drama K-Ville.
Brown returned to General Hospital on January 31, 2008 in the role of Claudia Zacchara. She announced on her Twitter September 16, 2009 that she would be leaving General Hospital in mid October 2009. Brown also announced on her Twitter account that she would be making an appearance on ABC's Castle.
In 2011 she had a supporting role in a Tracy J Trost film entitled The Lamp (All Things are Possible If You Just Believe). It is based on a novel by Jim Stovall. In July 2011, numerous soap outlets confirmed that Brown would join the cast of Days of Our Lives as Madison James, a successful Business woman. Her first appearance was October 4, 2011. In April 2012, it was announced that Brown had been let go from the series along with many other cast members.
In 2014, Brown played Massachusetts State Representative Katherine "Kate" Wesley in the soap opera web series Beacon Hill. She was nominated for a 2015 Daytime Emmy Award for Outstanding Performer in a New Approaches Drama Series, and won a 2015 Indie Series Award for Best Lead Actress (Drama) for the role.