Mobile interventions promoting positive body image are lacking. This study presents a randomized controlled evaluation of BodiMojo, a mobile application (app) intervention grounded in self-compassion to promote positive body image. A sample of 274 adolescents, mean (SD) age = 18.36 (1.34) years, 74% female, were allocated to a control group or used BodiMojo for 6 weeks. Appearance esteem, body image flexibility, appearance comparison, mood, and self-compassion were assessed at baseline, 6, and 12 weeks. Significant time by group interactions emerged for appearance esteem and self-compassion, with appearance esteem and self-compassion increasing in the intervention relative to the control group. These findings provide preliminary support for BodiMojo, a cost-effective mobile app for positive body image.