SummaryObesity prevention interventions with behavioral or lifestyle‐related components delivered via web‐based or telephone technologies have been reported as comparatively low cost as compared with other intervention delivery modes, yet to date, no synthesized evidence of cost‐effectiveness has been published. This study aimed to conduct a systematic review of economic evaluations of obesity prevention interventions with a telehealth or eHealth intervention component. A systematic search of six academic databases was conducted through October 2020. Studies were included if they reported full economic evaluations of interventions aimed at preventing overweight or obesity, or interventions aimed at improving obesity‐related behaviors, with at least one intervention component delivered by telephone (telehealth) or web‐based technology (eHealth). Findings were reported narratively, based on the Consolidated Health Economic Evaluation Reporting Standards. Twenty‐seven economic evaluations were included from 20 studies meeting the inclusion criteria. Sixteen of the included interventions had a telehealth component, whereas 11 had an eHealth component. Seventeen interventions were evaluated using cost‐utility analysis, five with cost‐effectiveness analysis, and five undertook both cost‐effectiveness and cost‐utility analyses. Only eight cost‐utility analyses reported that the intervention was cost‐effective. Comparison of results from cost‐effectiveness analyses was limited by heterogeneity in methods and outcome units reported. The evidence supporting the cost‐effectiveness of interventions with a telehealth or eHealth delivery component is currently inconclusive. Although obesity prevention telehealth and eHealth interventions are gaining popularity, more evidence is required on their effectiveness and cost‐effectiveness.