Feilhaber was born in Rio de Janeiro, Brazil on January 19, 1985. He was raised in his father's Jewish religion. His paternal grandfather emigrated from Austria to Brazil in 1938 to escape the Nazi regime. His family moved to Scarsdale, a suburb of New York City, when he was 6 and lived there for eight years.
After graduating from Northwood High School in Irvine, California in 2003, Feilhaber played college soccer at UCLA. At UCLA he was roommates with future national teammate Jonathan Bornstein. After his second year at UCLA, Feilhaber was called up by the U.S. U-20 national soccer team to play in the 2005 FIFA World Youth Championship in the Netherlands. He also represented the U.S. at the 2005 Maccabiah Games in Israel.
In July 2005, Feilhaber signed for Hamburg and played with the Hamburg reserve team in the third division, Regionalliga, for the 2005-06 season. On October 12, 2006, he made his Bundesliga, the German professional football association, debut in the second half. In August 2007, Feilhaber completed his signing with Derby County club of Derby, England. Derby released Feilhaber on a free transfer after being relegated from the Premier League after only one season. In August 2008, Feilhaber signed with Danish Superliga team Aarhus Gymnastikforening, commonly known as AGF.
Feilhaber was named to the U.S. Under-23 squad that competed at the 2008 Summer Olympics and the U.S. roster for the 2009 FIFA Confederations Cup. He was also a part of the 23-man squad for the FIFA World Cup 2010 in South Africa.