Thornton rejoined the Fire on December 5, 2022 after spending the 2022 season as the Houston Dynamo goalkeeper coach. Prior to joining the Dynamo staff, the Maryland native spent seven seasons as goalkeeper coach for D.C. United (2015-2021).

During his time with D.C. United, the team qualified for the MLS Playoffs on four occasions as Thornton oversaw the development of promising young goalkeepers. Before joining the ranks of MLS assistant coaches, Thornton served as associate head coach of the Villanova Wildcats (2013-2014), men’s and women’s goalkeeper coach at Elizabethtown College (2012) and volunteer goalkeeper coach at his alma mater Loyola College in Maryland (2012).

Prior to becoming a coach, Thornton began his Major League Soccer career with the New York/New Jersey MetroStars in 1996/1997 before joining the Fire for its 1998 expansion season, where he played until 2006. During that span, Thornton backstopped the team to the Domestic Double, winning the 1998 MLS Cup title and the 1998 Lamar Hunt U.S. Open Cup.

He was also anchored the team’s backline for three additional U.S. Open Cup trophies (2000, 2003 and 2006) and an MLS Supporters’ Shield title (2003). He is one of only three players in Club history to be a part of all six of the Fire’s domestic championships, alongside Chris Armas and C.J. Brown. After leaving the Fire, Thornton joined the Colorado Rapids in 2007, the New York Red Bulls in 2008 and closed out his playing career with Chivas USA from 2008-2011. At the international level, Thornton earned eight caps with the U.S. Men’s National Team from 1994-2001.