Me & You: Building Healthy Relationships (Me & You) is a multilevel, technology-enhanced adolescent dating violence (DV) prevention program that aimed to reduce DV among ethnic-minority, early adolescent, urban youth. A group-randomized control trial of Me & You, conducted with 10 middle schools from a large urban school district in Southeast Texas in 2014–2015, found it to be effective in reducing DV perpetration and decreasing some forms of DV victimization. Economic evaluations of DV interventions are extremely limited, despite calls for more economic analyses to be incorporated in research. We help fill this gap by evaluating the cost-effectiveness from the payer and societal perspectives of implementing the Me & You program. Using cost data collected alongside the Me & You group-randomized trial, we computed incremental cost-effectiveness ratios. Our primary outcome was “any DV perpetrated” within 12 months of the intervention. We conducted a cost–benefit analysis beyond the intervention endpoint by using literature estimates of per-victim lifetime costs of DV. We performed sensitivity analyses to assess effects of uncertain parameters. Under the base-case scenario, the cost of the Me & You curriculum compared to the standard curriculum was $103.70 per-student from the societal perspective, and the effectiveness was 34.84 perpetrations averted, implying an incremental cost per perpetration averted of $2.98, which ranged from $0.48 to $73.24 in sensitivity analysis. Thus, we find the Me & You curriculum is cost-effective and cost-saving in most scenarios. Policymakers should carefully consider school-based DV prevention programs, and cost data should be regularly collected in adolescent prevention program evaluations.