Mediate grew up in Southlake, Texas, attended Carroll High School, played club soccer for Dallas Solar, and played college soccer at the University of Maryland, making 3 consecutive College Cup appearances.

After a year with the Crew, appearing in 11 games (four starts) with one goal and an assist, he was traded to D.C. United on March 14, 2006, for a 2007 draft pick.

The son of Stan and Chris Mediate, Domenic has four siblings: sister Angela, and brothers Carmine, Rocco, and Vincent.

Carmine is a golfer for Baylor University[10] and Vincent is an ODP soccer player for Dallas Solar Red.

[11] The siblings are distant cousins of PGA Tour professional golfer Rocco Mediate.