OBJECTIVE: Caring for patients with traumatic brain injury (TBI) during the transition from hospital to home can be psychologically challenging to caregivers. This study aimed to assess the effectiveness of a novel mobile health (m-health) transitional care intervention to reduce stress and burden of caregivers of patients with TBI and to reduce readmissions. METHODS: A randomized controlled trial was conducted with 74 caregivers of adult patients with moderate or severe TBI admitted to a referral hospital in Indonesia. An m-health application for Android mobile phones was designed including education and information for caregivers. The application included an online chat feature with weekly monitoring. The m-health transitional care intervention also included face-to-face education before hospital discharge. Primary outcomes were caregivers' stress and burden. Outcomes were measured at 3 time points: at hospital discharge, 2 weeks postdischarge, and 4 weeks postdischarge. Random Allocation Software was used for randomization of study participants. RESULTS: Final analysis included data of 37 caregivers in the intervention group and 37 caregivers in the control group. Stress within the intervention group decreased over time (P < 0.001, mean difference = 11.05). Between both groups, stress was significantly different at 2 weeks and 4 weeks postdischarge (P < 0.001). Caregiver burden showed similar results (2 weeks postdischarge P < 0.001 and 4 weeks postdischarge P < 0.001). Only 1 patient in the control group was readmitted to the hospital. CONCLUSIONS: The m-health transitional care intervention reduced stress and burden of caregivers of patients with moderate or severe TBI. Nurses should consider using m-health technologies to support caregivers in the transition from the hospital into the community.