He won the silver medal at the World Indoor Athletics Championships 1991 in Seville. In 1992 he won a gold medal with the American 4x400 m relay team at the Olympic Games in Barcelona. The same year, Valmon set his personal best of 44.28 s.
He is now the head track & field coach at the University of Maryland, and coaches a summer camp at the university. Married Meredith Rainey also an Olympic runner. Andrew Valmon is also a member of Phi Beta Sigma Fraternity Inc.