The Cubs recalled Roberts from Triple-A Iowa on Wednesday, Maddie Lee of the Chicago Sun-Times reports.
He'll be joining the big club as a replacement on the 26-man active roster for left-hander Justin Steele (elbow), who was placed on the 15-day injured list. Roberts will likely work in middle relief for Chicago after getting off to a strong start to the season at Iowa, with whom he struck out seven batters while walking none over three scoreless innings between his two appearances.