Henegan's Taekwondo career spanned the years 1979-2001. During that time he won numerous awards in four different decades. They included Canadian, Pan American, and North American Championships, as well as winning the 1981 World Taekwondo Games in Santa Clara, California. At that event he became the first North American to beat the Koreans in a World Championship Gold Medal match.
Darrell competed as a professional kickboxer from 1984-1996. He finished with a record of 25 wins and 2 losses, with 20 wins by KO. He held numerous titles and was a two-time world champion. In 1988 he won the FFKA Heavyweight Title by decisioning Jerry Rhome and in 1993 he won the ISKA Cruiserweight Championship with a win over Przemyslaw Saletta. One of Henegan's losses was in a 1990 unification bout with KICK/ISKA Heavyweight Champion Dennis Alexio. He also had one bout as a professional boxer, a four round unanimous decision over Daniel DesRoches in 1986.