Prior to his major success, Duhamel had won an IMTA modeling contest (his first runner-up was Ashton Kutcher). He got a huge role in 1999 when he won the role of Leo du Pres, a charming schemer, on the ABC soap opera All My Children. His work on the show, especially his character's pairing with Rebecca Budig's Greenlee Smythe, garnered critical acclaim. Duhamel often referred to Rebecca Budig as "Little Budig". In 2002, Duhamel earned a Daytime Emmy Award nomination for Special Fan Award for America's Favorite Couple shared with Budig, and won a Daytime Emmy Award for Outstanding Supporting Actor for his portrayal of Leo du Pres. Later that year, Duhamel opted to leave All My Children to pursue other acting opportunities.

In 2003, Duhamel landed a prime time role on the NBC show Las Vegas playing casino security agent, Danny McCoy. He succeeded James Caan as president of the Montecito after Caan departed at the end of the fourth season. Duhamel has also played the character on Crossing Jordan in a crossover arc. Duhamel has appeared on the big screen, landing roles in films such as 2004's Win a Date with Tad Hamilton! and 2007's Transformers. (wikipedia.org)