He began his professional career with A-League (now USL First Division) team Boston Bulldogs in 1999, playing three games, before joining Major League Soccer club Los Angeles Galaxy in May 1999. He was voted Most Valuable Player (MVP) in 2000 after scoring five goals and making five assists, and helped the club to win the CONCACAF Champions' Cup in 2000, the U.S. Open Cup in 2001 and the MLS Cup in 2002. He made 122 appearances for Galaxy in five seasons, scoring ten goals. In 2001, Elliott trained for two months with Manchester United in England, but eventually returned to the United States.