The present study aims to design and validate a governance framework for the sustainable competitiveness of transport cooperatives through a green transport development approach. Despite the potential role of transport cooperatives in pooling resources, organizing vehicle fleets, strengthening member participation, and facilitating the transition toward green transportation, the existing literature has predominantly focused on macro-level emission-reduction policies, fleet renewal, or general governance mechanisms, with limited attention to an integrated framework linking cooperative governance, sustainable competitiveness, fleet modernization, and green transport development requirements. This study is applied in terms of purpose and employs a qualitative approach based on systematic grounded theory. Data were collected through 28 semi-structured interviews with transport cooperative managers, policy and regulatory experts, transport economics specialists, and academic scholars, and were analyzed using MAXQDA. The analysis resulted in 305 final codes, 45 concepts, and 14 main categories, which were organized within a paradigmatic model comprising causal, contextual, intervening, strategic, and consequential conditions. The core category identified was “operational action plan of transport cooperatives,” which serves as a mechanism for linking resources, institutional support, and organizational capacities to specific, time-bound, and monitorable implementation actions. To validate the final framework, 10 experts in cooperative governance, transport policy, and green transport development participated in two rounds of evaluation. The level of agreement in the second round exceeded.80%. The findings indicate that enhancing the sustainable competitiveness of transport cooperatives requires an integrated package encompassing financial support, regulatory stability, human capital development and training, data-driven capabilities, stakeholder participation, fleet modernization, and environmental requirements. Accordingly, the proposed framework shifts the focus from fragmented policy interventions toward participatory, data-driven, and environmentally oriented governance, providing a mechanism for translating policies, resources, and institutional requirements into measurable, implementable, and evaluable action plans.