 On February 4, 2015, the St. Louis Cardinals signed Villanueva to a minor league contract that included an invitation to spring training.The Cardinals added him to their 40-man roster on March 30.On June 27, he pitched the last three innings of an 8–1 victory over the Cubs for his first save of the season, and did so again on August 7 against the Brewers in a 6–0 win.