On December 16, 2001, Fuentes was traded to the Colorado Rockies, along with José Paniagua and Denny Stark for Jeff Cirillo.

However, in 2005, Fuentes took over the closer role for the Rockies following the season-ending shoulder surgery of right-handed pitcher Chin-hui Tsao.

His 31 saves matched Dave Veres (1995) for the third highest single season total in franchise history, trailing only José Jiménez (41 in 2002) and Chacon (35 in 2004).

In June 2007, after blowing four saves within an eight-day period, Fuentes was demoted from his role as Rockies closer, losing the job to Manny Corpas.

[2] On December 31, 2008, Fuentes agreed to a two-year deal with the Angels to fill in the position as closer after Francisco Rodríguez left for the Mets.

[3] On July 5, 2009, Fuentes was elected to represent Anaheim in the 2009 All Star Game, at the time leading the majors in saves.

His difficulties led manager Mike Scoscia to call in young reliever Kevin Jepsen to close at certain times.

[10] In the same general timeframe, Fuentes made public statements critical Geren's management, as did former A's reliever Huston Street.

[10] Fuentes was designated for assignment on July 3, 2012, to clear a roster spot for returning pitcher Bartolo Colón.

Brian Fuentes has a wife (Barbara), his oldest son Giovanni, two fraternal twins, Benicio and Gabriella, and their youngest child Farrah.