Background and Objectives: The purpose of this study was to investigate the effects of microcurrent stimulation on pain, shoulder function, and grip strength in patients with rotator cuff repair. Materials and Methods: This randomized single-blind controlled trial was conducted on inpatients of the rehabilitation department, and included 28 patients who underwent rotator cuff repair. Participants were randomly assigned to the experimental group (n = 14), treated with microcurrent stimulation, and the control group (n = 14), treated with false microcurrent stimulation. The microcurrent stimulation administered to the experimental group underwent general physical therapy and microcurrent stimulation three times a week for 4 weeks. Results: Changes in pain, range of motion in shoulder, simple shoulder test, and grip strength were assessed before and after the intervention. Both groups showed a significant decrease in pain and shoulder function (t = 27.412, 22.079, 19.079, and 18.561; p < 0.001), and grip strength showed a significant increase (t = −8.251 and −9.946; p < 0.001). The experimental group that underwent microcurrent stimulation exhibited a significant effect on pain, shoulder function, and grip strength compared with the control group that underwent false microcurrent stimulation (t = −2.17, −2.22, and 2.213; p = 0.039, 0.035, and 0.036). Conclusions: This study confirmed that microcurrent stimulation is effective for the treatment of rotator cuff repair patients.