New England Revolution drafted Riley in the second round of the 2005 MLS SuperDraft, and he acquitted himself well in his rookie season, playing various positions and scoring a goal. He continued to keep himself in the mix in defense, starting the majority of the games in 2006 and 2007.
Riley was left exposed by Seattle in the 2011 MLS Expansion Draft and he was selected by expansion side Montreal Impact in the November 23, 2011, draft.[3] He was then immediately traded with allocation money to Chivas USA for Justin Braun and Gerson Mayen.[4] Riley was traded to D.C. United on February 14, 2013, for a 2015 Supplemental Draft pick.[5] The trade was later described as being part of a "systematic expulsion of players" at Chivas USA who did not fit the parent club's Mexican-only policy.[6]
Riley won his 5th US Open Cup title in 2013 with D.C. United. In the sixth minute of stoppage time there was on open header in the box from Álvaro Saborío that Riley was able to deflect onto the cross bar to prevent extra time.[7]
After his release from D.C. United, Riley trialled with and was eventually signed by LA Galaxy as a free agent.[8]
On March 6, 2015, he signed with Colorado Rapids. During the 2015 season, Riley made 17 appearances in all competitions, scoring a lone goal on May 8, 2015, against former club San Jose in the third minute of stoppage time to salvage a 1–1 draw. The Rapids declined their option on Riley on December 3, 2015.
Riley formally announced his retirement as an active player on June 23, 2016.[10] One month prior, he had been appointed MLS's director of player relations, a position that had been vacant since Ali Curtis became the New York Red Bulls sporting director in December 2014.[11] In April 2018, it was announced that Riley would take a position on the broadcast team for the Seattle Sounders and their USL affiliate team, Seattle Sounders FC 2.[12][13]
Riley was born in Colorado Springs, Colorado, to an African American father and a Korean mother. His parents divorced a year after he was born. Riley and his sister were raised by his mother in the Denver area.[16]
