Denis Hamlett was born in Puerto Limon, Costa Rica, and grew up in Maryland. He played college soccer at George Mason University before joining the Fort Lauderdale Strikers of the American Soccer League in 1992.
Hamlett played in both the American Soccer League, the NPSL and Continental Indoor Soccer League before being selected in the second round of the inaugural MLS draft in 1996 by the Colorado Rapids. The defender appeared in 31 games for Colorado before retiring at the end of the 1996 season.
Hamlett transitioned to coaching in 1997, earning his coaching license from U.S. Soccer and joining the Chicago Fire staff as an assistant prior to the 1998 season, the same year Marsch joined the Fire from D.C. United. He was named first assistant in Chicago in 2001, and served as interim head coach briefly in 2007, and was named head man for the 2008 season. Under Hamlett, the Fire reached two straight MLS Eastern Conference Finals, as well as the 2009 SuperLiga Final.
Hamlett has also done coaching stints with the Vancouver Whitecaps, and was part of Marsch’s staff in Montreal in 2012.