 He was part of the Uruguay squad for the 2010 World Cup and one year later, he won the 2011 Copa América, earning him his first international honour, despite not making an appearance in the competition.Castillo began his football career at the local amateur club Santa Bernardina of his natal city Durazno, in where he played in the youth ranks of the team during 1989 to 1997.In 1998, he joined as youth player to Defensor Sporting.