Castrillón began his career with top Colombian side Independiente Medellín in 2002. As one of the top midfielders in Colombia he helped Medellín in capturing the Colombian Primera A title in 2002 and 2004. He appeared in almost 300 appearances with "El Poderoso de la Montaña" in his eight years with Medellín. In 2009 he left Colombia and joined Chinese club Nanchang Bayi, remaining at the club for one year. In 2010 he returned to Colombia, this time as the star signing for Once Caldas ahead of its participation in the 2010 Copa Libertadores, and was once again a key figure in helping his new club capture a Colombian Primera A title. In 2011 he returned to Independiente and had a fine season scoring 11 goals for the club.
Castrillón made his debut for Colombia in 2004. He has been a prominent member of the national squad appearing in 29 games for his nation. He played in Copa América 2004 and Copa América 2007 scoring in the 2007 tournament. Also in the Colombian national football team he scored 4 goals in a match against America.