He is best known for playing Tad Martin on the soap opera All My Children. His first stint on the show ran from 1982-1986. He returned from 1988-1990 and again from 1992-present. Knight also appeared as Ted Orsini on AMC in 1993.
His reason for leaving the show was to pursue acting projects on the West Coast, which included a starring role in the feature film Date with an Angel, and various primetime appearances — including Murder, She Wrote, Dear John and Grapevine. Knight co-starred in the off-Broadway play Wrong Turn at Lungfish, and he appeared in the ABC movie for television, She Stood Alone: The Tailhook Scandal, and in the off-Broadway Cakewalk, with Linda Lavin.
Knight attended Wesleyan University and graduated in 1980, a year ahead of schedule.
Knight was honored with two Daytime Emmy Awards for 'Outstanding Younger Leading Actor' (1986 and 1987). In 2001, he was honored with his third Daytime Emmy Award. He also received the 1997 Soap Opera Digest Award for 'Best Supporting Actor' and a nomination in the same category in 1998.
In real life, he has been married since June 27, 1992 to One Life to Live star Catherine Hickland. In January 2006, the couple announced that they are getting a divorce after 14 years of marriage and the two will remain friends.
The couple were honored for their charitable work by the West End Intergenerational Residence in Manhattan in 1999.