Despite the broad academic and political interest aroused by the ecosystem concept, little scientific attention has been paid to its social dimension and especially to the social economy enterprises ecosystems. This paper aims to conceptualize the latter by establishing its defining features and its goals, and to provide empirical evidence from two worldwide known social economy ecosystems, one in the Valencia region of Spain and the other in the Emilia Romagna region of Italy. The results show that the balance between the economic objectives and the creation of social value and social innovation, collective social entrepreneurship and specific institutional components are key features of social economy ecosystems. The proactive role of the axiological, cognitive and institutional elements of these ecosystems, embedded in knowledge and culture, enable, when properly applied to an operational sphere, the achievement of social value and the start-up and scaling up of the social economy model.