Romero played college baseball at the University of Mobile. Romero was traded by the Twins to the Angels on December 9, 2005, for infielder Alexi Casilla. Romero was one of the Puerto Rican players to agree to play for Puerto Rico in the 2006 MLB World Baseball Classic. On October 6, 2006, the Angels declined his contract option for 2007, making him a free agent. On December 15, he signed a 1-year deal with the Boston Red Sox. However on June 9, 2007, he was designated for assignment, and then released on June 19, 2007.