This study focuses on digital platform cooperatives (DPCs) and investigates how social value is created within platform cooperativism for fostering a more equitable and inclusive digital landscape. We explore and theorise the outcomes of social value creation by DPCs and identify the generative mechanisms that drive their emergence. We do this by adopting a Critical Realism philosophical stance, in combination with Grounded Theory techniques based on the Straussian version of coding. Our data is drawn from 36 interviews with DPC (co-)founders, members, and experts, alongside an array of documentary data from DPCs across 12 European countries. Our analysis reveals three outcomes of social value creation by DPCs: strengthening community capacities, federating cooperative ventures, and fostering practices for narrative co-creation. Additionally, we identify two generative mechanisms with enduring properties and explanatory power: collective identity and empowerment, and government-community symbiosis. These mechanisms are identified through retroductive theorising, offering plausible explanations for the outcomes of social value creation, situated within relevant contextual conditions, such as grassroots mobilisation and advocacy, institutional commitment and policy support, and legislative frameworks for cooperative integration. This study contributes to the understanding of social value creation in platform cooperativism as an endeavour to co-construct a cooperative value ecosystem, providing valuable insights for both theory and practice.