This study assessed the effects of a 12-week afterschool mindfulness-based diet and exercise intervention on mental and physical health in Latinx and Black youth. One hundred forty-eight boys and girls (average age = 10.1 years, SD = 1.3 years; 52% girls; 72.3% Latinx) were randomized to either the experimental group (n = 80) or the control group (n = 68). The experimental group participants engaged in fitness yoga, kickboxing, and/or spinning sessions, and mindfulness practices (e.g., breathing, meditation, and mindful eating) twice per week for 12 weeks. The control group participants engaged in a recreational play session once per week for 12 weeks. All participants completed surveys (demographics, acculturation, anxiety, emotional eating, sleep, and food intake) and had their height, weight, and percent body fat measured pre- and post-intervention. Participants wore an accelerometer for 7 days pre- and post-intervention. Repeated measures analysis of covariance indicated that the experimental group participants reported lower scores in emotional eating, anxiety, and sleep latency post-intervention compared to the control group participants. Conversely, no significant differences were observed in physical activity between the experimental and control group participants post-intervention. These findings indicate that a mindfulness-based intervention has a positive effect on emotional eating, anxiety, and sleep latency among youth of color.