This study systematically reviews the scientific literature on the role of open innovation in addressing current and emerging societal and environmental challenges. To do so, we analysed the what, how, who and why of integrating external partners for sustainability purposes. We found a clear predominance of open innovation mechanisms to develop environmental innovations rather than innovations focused on a triple bottom line. We identified at least four mechanisms associated with the inbound mode of open innovation (crowdsourcing, lead‐user workshops, intermediation, and experiments and discussion sessions) and 10 mechanisms related to the coupled mode of open innovation (alliance, business‐non‐profit engagement, co‐creation, joint ventures, cooperation, collaborative innovation contests, coopetition, cross‐sector partnerships, joint development projects, and innovation networks). Even though sustainability‐oriented innovation promises to be a source of societal transformation and entrepreneurial opportunities, we found that firms can face some tensions when simultaneously addressing financial, environmental and social purposes.