Innovation contests are increasingly used by businesses as an instrument for open innovation to address sustainability related questions. However, according to the open innovation literature, one of the main pitfalls of this approach can be the mismatch between the solutions proposed by non-experts and the companies’ capabilities to implement such solutions. We introduce the concept of collaborative innovation contests – where companies actively collaborate with non-experts – as a way to address this mismatch. Through participant observations, we analyse the process of a sustainability-oriented collaborative innovation contest guided by design-thinking. Our results indicated that the combination of an open innovation contest and design thinking could, through the creation of constant feedback loops, lead to increased collaboration between the contests participants, the companies proposing a challenge, and other relevant stakeholders. However, our results also highlighted trade-offs between the innovativeness of ideas, the alignment of solutions with firm capabilities and the resources needed for collaborative innovation contests. We conclude that, through the involvement of different stakeholders, their ideas and perspectives, collaborative innovation contests are a useful approach to generate a comprehensive understanding of the sustainability challenges companies face.