Marsh had a brief stint with the NFL'sTennessee Titans in 2001, but missed the whole season due to injury. The B.C. Lions signed him as a free agent in 2004, in which Marsh recorded his career-high 61 tackles. In 2005, he started all 18 games, and had 47 defensive tackles and 7 special teams tackles. In 2006, Marsh had a career-high 4 interceptions as well as 52 tackles. He helped BC win the 2006 Grey Cup. Marsh is regarded as one of the best cornerbacks in the CFL and he was named a CFL All-Star in 2008. Entering his 10th season as a BC Lion, at age 32, he was awarded a contract extension.