He appeared on "General Hospital", "One Life to Live" and "As the World Turns", where he played both good guys and villains. In 2003, Mantooth joined the cast of "As the World Turns" as a temporary replacement for Benjamin Hendrickson in the role of Hal Munson. When Hendrickson left the series in 2004, Mantooth returned to the series as Munson, in a recurring position until Hendrickson returned to the program in 2005. In 2007, Mantooth landed the recurring role of Kirk Harmon on "One Life to Live".