BackgroundDeciding whether and how to disclose one’s autism at work is complex, especially for autistic youth and young adults who are newly entering the labor market and still learning important decision-making and self-determination skills. Autistic youth and young adults may benefit from tools to support disclosure processes at work; however, to our knowledge, no evidence-based, theoretically grounded tool exists specifically for this population. There is also limited guidance on how to pursue the development of such a tool in collaboration with knowledge users.ObjectiveThis study aimed to co-design a prototype of a disclosure decision aid tool with and for Canadian autistic youth and young adults, explore the perceived usability of the prototype (usefulness, satisfaction, and ease of use) and make necessary revisions, and outline the process used to achieve the aforementioned objectives.MethodsTaking a patient-oriented research approach, we engaged 4 autistic youths and young adults as collaborators on this project. Prototype development was guided by co-design principles and strategies, and tool content was informed by a previous needs assessment led by our team, the autistic collaborators’ lived experiences, considering intersectionality, research on knowledge translation (KT) tool development, and recommendations from the International Patient Decision Aid Standards. We co-designed a web-based PDF prototype. To assess perceived usability and experiences with the prototype, we conducted 4 participatory design and focus group Zoom (Zoom Video Communications) sessions with 19 Canadian autistic youths and young adults aged 16 to 29 (mean 22.8, SD 4.1) years. We analyzed the data using a combined conventional (inductive) and modified framework method (deductive) analysis to map the data onto usability indicators (usefulness, satisfaction, and ease of use). Grounded in participants’ feedback, considering factors of feasibility and availability of resources, and ensuring tool fidelity, we revised the prototype.ResultsWe developed 4 categories pertaining to the perceived usability of and participant experiences with the prototype: past disclosure experiences, prototype information and activities, prototype design and structure, and overall usability. Participant feedback was favorable and indicative of the tool’s potential impact and usability. The usability indicator requiring the most attention was ease of use, which was prioritized when revising the prototype. Our findings highlight the importance of engaging knowledge users throughout the entire prototype co-design and testing processes; incorporating co-design strategies and principles; and having content informed by relevant theories, evidence, and knowledge users’ experiences.ConclusionsWe outline an innovative co-design process that other researchers, clinicians, and KT practitioners may consider when developing KT tools. We also developed a novel, evidence-based, and theoretically informed web-based disclosure decision aid tool that may help autistic youth and young adults navigate disclosure processes and improve their transitional outcomes as they enter the workforce.