Allen made his MLS debut in the Galaxy's first match of the 2008 season against the Colorado Rapids on March 29, 2008. He scored his first MLS goal on June 7, 2008, also against the Colorado Rapids. On February 25, 2009, Allen was waived by the Galaxy[1] due to frequent injury.
Following an unsuccessful trial with MLS expansion side Seattle Sounders FC due to illness, and having been unable to secure a professional contract elsewhere, Allen joined the Seattle Wolves of the USL Premier Development League on May 6, 2009. He went on to score 6 goals and contribute 6 assists in the 16 games he played for them.
On July 24, 2009, D.C. United announced it had signed Allen.[2] He made his United debut in a friendly against Real Madrid on August 9, 2009, and made a couple of appearances for the team in the CONCACAF Champions League, but did not feature in league play, and was waived at the end of the season.[3]
On March 31, 2010, Allen was signed as a player for the newly formed club NSC Minnesota Stars.[4]
As of March 14, 2012, the Stars announced that Allen had been released from the team for unspecified reasons.