Warner attended Denver East High School, played club soccer for Colorado Rush, and spent time training with English Premier League players and coaches at the Liverpool Youth Academy in 2002, before playing four years of college soccer at the University of Portland. He was named to the All-West Coast Conference Freshman Team and received an All-WCC Honorable Mention as a rookie in 2006, was named to the All-WCC First Team and to Top Drawer Soccer’s All-Season Third Team in 2007, and was named to the All-WCC First Team for the second consecutive year in 2008, when he … led the Pilots with eight assists and was second on the team with five goals.
During his college years Warner also played for both Colorado Rapids U23’s and Portland Timbers U23 in the USL Premier Development League.