Purpose: This paper aims to explore the effects of collaborative innovation (CI) in urban planning practice by investigating the influence of a platform for collaboration between academia and external partners (practitioners and community groups). Unlike previous research on learning outcomes from the perspective of students (Fokdal et al., 2020), the aim of this article is to investigate the transformative learning (TL) experience from the perspective of the external partners. Design/methodology/approach: The outcomes of the TL experience were assessed through four elements: disorienting dilemma; critical reflection; engagement in discourse; and reflective and critical taking action. Findings: The claim that collaboration with multiple actors through TL processes can help promote innovative ways to view and practice planning outside of academia has to a certain extent been confirmed. This paper provides evidence that such transformative processes can have an impact on the individuals involved and shows the importance of individuals acting as change agents--or drivers of innovation. In addition, the importance of a collaborative platform--acting as an intermediary--in facilitating TL processes in planning practices is highlighted in the context of Serbia. Originality/value: This paper is a continuation of existing research on educational initiatives that attempt to integrate sustainability into the curricula and bring innovation to urban planning practice; showcase outcomes of the TL experience for sustainable development, especially when addressing the innovative ways that planning is practiced outside of academia; and push for change toward a more sustainable future not only within and but also outside of academia.