Many threats to biodiversity are the result of human actions, which means that changing human behavior can positively alter the trajectory of our current biodiversity crisis. While there is an increasing number of behavior change interventions being implemented in biodiversity conservation, their design is rarely informed by the people they try to influence, thereby lowering the probability of success. Building successful interventions requires substantial audience research, but this can be challenging for conservation projects with perennially limited time and resources. Here, we critically discuss co-design as a useful and effective approach for gathering audience insights relatively quickly, allowing conservation practitioners to integrate end-user voices when they would otherwise be excluded from intervention design. Specifically, we present a seven-step co-design process, providing an outline and guidance for how to generate more user-centric intervention ideas and transform them into feasible prototype interventions. Further, we show how we applied this seven-step process with coffee consumers in a sustainable conservation context. This study outlines contributions that showcase the value of user-centered design approaches to behavior change interventions for biodiversity conservation.