Background: The purpose of this study was to pilot-test an adapted obesity prevention intervention called Preventing Obesity Using Digital-Assisted Movement and Eating (ProudMe) in under-resourced schools. Method: Six schools were randomized to either ProudMe (n = 33 participants at three schools) or waitlist control (n = 46 participants at three schools) groups. ProudMe targeted students’ physical activity, diet, and screen time through interventions in school cafeterias (i.e., ProudMe Cafeteria) and physical education programs (i.e., ProudMe PE), and via artificial-intelligence-assisted behavioral counseling (ProudMe Tech) and staff professional development (ProudMe PD). Mixed methods data were collected to assess three implementation outcomes including penetration, fidelity, and sustainability. Trained observers evaluated the school cafeterias using the Smarter Lunchroom Scorecard before and after the intervention. Trained data collectors pre- and post-tested participants' anthropometrics (weight, height, waist circumference) and health behaviors. Results: ProudMe Cafeteria demonstrated outstanding implementation outcomes. The ProudMe Cafeteria intervention led to a 13.4% improvement (ΔM = 4.7) in scorecard scores across three schools, while control schools saw a 9.8% decline (ΔM = -3.0). ProudMe PE demonstrated only moderate penetration (50% to 67%) and fidelity (fidelity index ranged from 50% to 68.8% (M = 62.5%)) with low sustainability. ProudMe PD was well attended but ProudMe Tech was under-utilized. No significant time-by-condition interaction effects were observed for the student-level anthropometric and health behavior outcomes. Conclusion: This pilot trial generated mixed evidence on feasibility of the pilot ProudMe intervention. The lessons learned from this pilot study will inform our future intervention refinement for effectiveness evaluation. Childhood obesity prevention intervention efforts in under-resourced schools should consider influential factors such as intervention characteristics, outer setting, inner setting, characteristics of the individuals involved, and the implementation process.