On 18 December 2009, Castillo had reached an agreement with the Colombian Primera División side Deportivo Cali, putting pen to paper on a one-year deal. On 21 December, the player presented as new keeper of the club during a press conference. His competitive debut came against Deportes Tolima in a 3–1 loss where Jorge Perlaza's netted a hat-trick. However the next game Castillo had a better performance against Millonarios which Cali won 4–1 and then began to reach a well level that allowed him be nominated in the 23-man Uruguayan squad to face the 2010 FIFA World Cup at South Africa.