Purpose The present study aims to evaluate the effectiveness of a mobile-assisted empowerment program developed specifically for caregivers of cancer patients undergoing radiotherapy. Methods In this study, seventy-four individuals who gave care for cancer patients that received radiotherapy between September 2019 and May 2020 were randomized to receive a mobile-assisted empowerment program or standard care. The mobile-assisted empowerment program comprised of education and information related to the radiotherapy process, videos, activities, and question-and-answer modules to support caregivers during the radiotherapy process. Outcome measures were collected at baseline (day 1 of radiotherapy) and on day 21 and included caregiver demographics, distress, quality of life, and coping style using validated questionnaires. Results Compared with baseline, individuals' mean scores of distress were lower in the empowerment group than the control group (p< 0.001). General quality of life and sub-dimension mean scores were higher in the empowerment group than the control group (p <= 0.05). There was no difference in the coping style average scores (p >= 0.05) between the two groups. Conclusions This study supports the findings that a mobile-supported empowerment program reduced the level of caregiver distress and increased quality of life during their loved one's treatment with radiotherapy.