In March 1998, the Tampa Bay Mutiny selected Keller in the first round (seventh overall) in the 1998 MLS College Draft.
He played nine games for the Mutiny in 1998 before being traded to the Chicago Fire on June 29, 1998, in exchange for Jorge Salcedo.
When the Mutiny folded in 2001, the Dallas Burn selected Keller in the first round of the 2002 MLS Dispersal Draft.
He elected to retire from professional soccer and joined Morgan Stanley, a financial services company.
In January 2005, Keller moved to Proactive Sports Management, where he is currently the director of marketing.