Adolescent survivors of sex trafficking are at risk for poor health outcomes and may be less likely to adopt healthy lifestyle behaviors such as physical activity. Survivors of childhood traumas may be less likely to engage in physical activity due to lack of self-efficacy. The present study was a case-series of a pre-post, single-arm physical activity intervention to test whether the program could increase self-efficacy among adolescent survivors of sex trafficking. The intervention was 8-weeks of 60-minute aerobic physical activity classes offered three times per week at a residential center for adolescent girls who are survivors of sex trafficking and sexual abuse. The primary outcome was physical activity-related self-efficacy as measured by the Sport Competence subscale of the Physical Self Perception Profile (PSPP) questionnaire. Secondary outcomes included self-reported physical activity, emotional eating, and sleep habits. All outcomes were measured at baseline, 4 weeks, and 8 weeks. Five participants were enrolled in the study. Two participants experienced an increase in the Sport Competence subscale of the PSPP Questionnaire by Week 4 of the study and then a decrease by Week 8 of the study. Another participant experienced no change in the Sport Competence subscale score. Scores for the last two participants could not be determined due to invalid data. These findings suggest that more research is needed on enhancing healthy behaviors among adolescent sex trafficking survivors.