The 23-year-old stopper was granted a permit by the Home Office and will thus head to Villa Park upon the conclusion of the Olympic Games.
In a statement the 2007 MLS Goalkeeper of the Year said, "For the past three and-a-half years, it has been my privilege to represent Chivas USA and its passionate fanbase.
"As I begin this new phase of my career, I will continue to draw upon the lessons learned from my Chivas USA teammates and coaches, as well as the support I received from the organization and its fans.
"As my very first professional club, Chivas USA will always have a special place in my heart."
Chivas president Shawn Hunter praised his former 'keeper upon his departure, saying, "Brad was the first goalkeeper to defend the colors of Chivas USA in Major League Soccer.
"This organization has seen him grow from a 20-year-old rookie to a U.S. Olympian, the reigning MLS Goalkeeper of the Year and now a member of one of England's great clubs.
""We trust that Villa supporters will soon see what Chivas USA fans have known for some time: that this is a very special young man with the potential of becoming one of the great goalkeepers in the international game."
Indeed, on the surface Villa appear to have landed a fine galkeeper. Guzan, an alumnus of the University of South Carolina, was the second MLS SuperDraft pick overall of the 2005 season. An injury to Martín Zúñiga saw him make 24 appearances in his first season and win the Rookie of the Year award.
In 2006 he made his international debut, while his Goalkeeper of the Year award in 2007 came off the back of 13 clean sheets in the MLS.
"It is an honor for Chivas USA to see its one of its players transfer to one of England's storied clubs," added Chivas USA coach Preki. "Although Brad will be missed, we very are happy for him and wish him luck with the challenges ahead."
Guzan is nw under pressure to perform at the Olympic Games before heading for Birmingham, where he is likely to serve as understudy to his countryman Brad Friedel.
Steve Michaels, Goal.com