On June 24, 2008, Ildemaro Vargas signed with the St. Louis Cardinals as an international free agent. He made his professional debut with the VSL Cardinals and then split last year between the GCL Cardinals and Low-A Batavia Muckdogs. Vargas made the Chicago Cubs roster, but did not play for the team during the season. In 2013, he was designated for assignment and sent to Triple-A Iowa.