[2] He was selected by the Chicago White Sox in the 36th round of the 2018 Major League Baseball draft, but did not sign and instead enrolled at the University of Miami.
[16] To begin his professional career, he was assigned to the Rookie-level Arizona Complex League Diamondbacks before being promoted to the Visalia Rawhide of the Low-A West after two games.
Del Castillo was assigned to the Hillsboro Hops of the High-A Northwest League to begin the 2022 season, but also played briefly with the ACL Diamondbacks and Visalia.
[22] On August 9, against the Philadelphia Phillies, Del Castillo became the first Diamondbacks player in franchise history to have a walk-off home run as their first in the major leagues.
[23] On August 18 against the Tampa Bay Rays, Del Castillo hit a three-run home run that tied the game in the ninth, but the Diamondbacks lost in extra innings.