DeJong (back) will join the Cardinals in Seattle on Sunday and will likely be activated off the injured list, Derrick Goold of the St. Louis Post-Dispatch reports.
DeJong has been out for the entirety of the season so far while recovering from his back injury. The 29-year-old will likely be back on the roster for the finale against the Mariners, and he should serve in a utility role while he's a member of the club.