Forest management plans are central to regulations governing logging concessions in the Congo Basin, yet their long-term effectiveness remains uncertain. Here, we combine annual satellite-derived forest change data with administrative concession records and exploit variation in the timing of plan validation across five countries to assess how validation influences forest-cover dynamics from 2000 to 2020 using counterfactual impact-evaluation methods. We find that concessions with validated plans experience a gradual, sustained decline in forest loss, averaging 100 ± 44 hectares per year, equivalent to a 47% reduction relative to concessions operating without validated plans. Effects persist for up to 19 years and occur in concessions with and without independent third-party certification. These results indicate that accelerating the validation and implementation of forest management plans can substantially reduce forest disturbance in the Congo Basin.