This study presents an mHealth-based intervention using wearable devices and personalized sports prescriptions to improve adolescent physical health. A 12-week experiment was conducted with 312 junior high school students, randomly assigned to intervention and control groups. The intervention group received customized exercise plans supported by real-time physiological monitoring in addition to regular physical education; the control group followed standard classes only. Data on physical fitness (body mass index [BMI], lung capacity, 50-meter run, grip strength) and mental well-being were collected. Results showed significant improvements in the intervention group across all physical indicators (p < 0.05). The findings suggest that integrating wearable technology and data-driven prescription models into school health programs can effectively promote adolescent health, offering a scalable digital health solution within educational settings.