The Cubs acquired Zulueta from the Mariners on Monday in exchange for cash considerations.
Seattle designated Zulueta for assignment Wednesday, but he'll regain a spot on the 40-man roster with his move to a new organization. The right-hander has posted an inflated 5.75 ERA over 20.1 innings in 22 appearances with Triple-A Tacoma so far this season, but he boasts impressive velocity and has struck out 21.4 percent of the batters he's faced. The Cubs are expected to assign him to Triple-A Iowa.