Co-design approach is increasingly popular in many organizations that address global change and social sustainability challenges, thanks to its unique and diverse methods of engaging relevant people in design processes and decision-making. However, the social distancing led by the COVID-19 pandemic seriously problematized the traditional in-person co-design activities. A sustainable online transition is unprecedentedly pressing. By acknowledging the limitations of online co-design, i.e., lack of means for participant engagement, we argue that gamification holds great promise for online co-design. This paper presents an empirical study to investigate this potential qualitatively. Based on the data collected from three gamified online co-design implementations, we examine the benefits of gamification and how future activities should be designed and implemented from the participants’ perspectives. Based on the participants’ perceptions, we propose several recommendations for designing impactful gamification. The finding suggests that gamification can facilitate online co-design activities in an enjoyable, relaxing, structuring, and creative manner, since they are perceived and recognized by the participants. Moreover, the successful implementation of online co-design implies that great sustainability benefits can be achieved through online transition, i.e., reducing paper consumption and time spent on meetings and unproductive discussions, supporting extensive diversity and density in representation. Online can enable this by overcoming not only the geographic and time limitations but also relevant social issues.