The aim of this paper is to collect evidence-based experience on a co-creation multi-stakeholder participatory process in a non-formal academic environment. We use the Sustainable Development Goals (SDGs), the “6i model,” and a participatory approach as background methodologies. Within the long-lasting process of collaboration with Eurochild (Eurochild advocates for children’s rights and well-being to be at the heart of policymaking. A network of almost 200 organizations internationally recognized for its work to promote children’s rights and well-being. It influences policies, builds internal capacities, and facilitates mutual learning and exchanges of practice and research), the event started with an open session followed by a World Café dynamic with 50 participants from different age groups (13–81), cultures (Spain, United Kingdom, Finland), professions, academic fields, and socioeconomic backgrounds. Several types of data were collected: participant observation during four months (20 h), informal communication with participants, and three in-depth interviews. Based on overall analysis, the application of both the 6i model and the child participation approach had an impact on three different levels: (1) in the functioning of the core group; (2) in the experience of the participants in the event; and (3) in the final outcome of the whole process.