The Guardians optioned Halpin to Triple-A Columbus on Sunday, Tim Stebbins of MLB.com reports.
The 24-year-old was called up by Cleveland in mid-June and played 10 games during this stint in the majors, going 4-for-23 with a triple, five runs and eight strikeouts. Halpin is heading back to Columbus to clear space for the return of Chase DeLauter (rib) from the injured list.