BackgroundMental illness stigmarefers to damaging stereotypes and emotional responses around the experience of mental health issues. Media-based interventions have the potential to reduce the public’s stigmatizing attitudes by improving mental health literacy, emotional appeal, and the intimacy of address. As audio-based media facilitating storytelling, podcasts show potential for reducing stigma; however, it is unclear what features could make a podcast effective or engaging.ObjectiveThe Co-Design and Anti-Stigma Podcast Research (CASPR) study aimed to collaborate with key target audience members to inform the development of a new podcast. This podcast primarily aims to reduce listeners’ stigmatizing attitudes toward people living with complex mental health issues.MethodsThis study was adapted from Experience-Based Co-Design methodology. The first part,information gathering,involved a web-based mixed methods survey with 629 Australian podcast listeners to explore their interest and concerns around podcasts. Then, a series of focus groups were held with a purposive sample of 25 participants to explore the potential benefits and challenges of the podcast format. Focus group participants included people with lived experience of complex mental health issues, media and communications professionals, health care professionals, and people interested in workplace mental health. The second part,co-design,constituted 3 meetings of a co-design committee with 10 participants drawn from the focus groups to design the podcast using brainstorming and decision-making activities.ResultsMost survey respondents (537/629, 85.3%) indicated a willingness to listen to a podcast about experiences of mental illness stigma; participants indicated preference for semistructured episodes and a mixture of light and serious content. Focus group participants identified potential challenges with appealing to listeners, making the content emotionally resonant and engaging, and translation to listeners’ attitude change. The co-design committee collaborated to achieve consensus on the focus of individual episodes: domains where stigma and discrimination are common, such as workplaces and health care settings; the structure of individual episodes: storyboards that centralize guests with lived experience, featuring explicit discussions around stigma and discrimination; and overarching content principles, including a sincere, empathetic, and hopeful tone; using plain language; having clear calls to action; and providing listener resources.ConclusionsThe co-design process informed a podcast design that features lived experience narratives with an explicit focus on stigma and discrimination, highlighting the realities of stigma while acknowledging progress in the space and how listeners can contribute toward social change. This study allowed for an in-depth discussion around the strengths and limitations of such a podcast according to different target audience members. The co-design committee designed key elements of a podcast that has the potential to minimize the limitations of the format while embracing the benefits of podcast-based storytelling. Once produced, the podcast will be evaluated for its impact on attitude change.