He was a 1996 Olympic Games gold medalist in the men's 4×400 meter relay for the United States.

He has a career best of 44.13 in the 400 m. After going to college at Georgia Tech in Atlanta and winning the 1994 NCAA Championship in the 400 m at Boise, Idaho, Mills ran to a #2 World Ranking behind Michael Johnson—breaking 45.00 seven times that year.

A native of Washington, D.C., Mills attended DeMatha Catholic High School in Hyattsville, Maryland.

He is currently an assistant track and field coach at Tulane University in New Orleans, Louisiana.

He grew up visiting his third cousins on Camp Branch, Dave, Daryl, Kelly and DeWayne.