Innovation contests open to the public, are increasingly used by businesses as an instrument for open innovation, and in recent years, to address sustainability related questions. However, according to the open innovation literature, one of the main pitfalls of the solutions developed by non-expert designers can be the mismatch between the idea proposed, and the companies’ actual capabilities to implement such solutions. Companies’ involvement throughout the planning, co-creation, and evaluation phases of the innovation contests, can potentially address this mismatch. Through participant observations, the authors followed the design, development, and final outcome of a “sustainable innovation challenge”. Each of the 16 participating companies proposed a challenge in one of the fields of circular economy, energy efficiency, social innovation, or ‘sustainable’ organizational initiatives. A series of workshops were then facilitated using design-thinking principles. Solutions to the proposed questions were co-created by company’s members with volunteers participating in the challenge as well as target users. Our data suggest that innovation contests open to the public, developed and assisted by organization’s members, are useful as vehicles for experimentation for sustainability-oriented innovation. The outcomes of the contests, however, were perceived by the participants as effective to create new collaborations, and to deepen the understanding of the sustainability problem, as opposed to providing radical solutions to these problems.