Castillo played for Cuba in the 1993 World Junior Championships in Windsor, Ontario, at which time he defected.

[3] That offseason, he was traded by the Giants to the New York Yankees in November 1997 as part of a package for Charlie Hayes.

The White Sox released Castillo during spring training, and he spent the 1999 season with the Schaumburg Flyers of the independent Northern League.

In 1999, Castillo would pick up the bat again and came to the plate 26 times (mostly as a pinch hitter but did play five games at first base) hitting .348/.407/.739.

After missing 2005 due to elbow surgery,[1] Castillo played for the Atlantic League's Road Warriors in 2006 and the beginning of 2007.

[3] Castillo finally returned to affiliated baseball when he was signed to a minor league contract by the Baltimore Orioles for the 2008 season.

He began that season with the Baltimore Orioles' Triple-A affiliate, the Norfolk Tides,[3] before making his major league debut on April 28, 2008, in the 13th inning against the Chicago White Sox, he faced one batter and picked up the win.

On April 4, 2015, Castillo signed with the Diablos Rojos del Mexico of the Mexican Baseball League.

Castillo signed with the Joplin Blasters of the American Association of Independent Professional Baseball following his release.