Background: Additional evidence is required to address the unintended consequences of medication use in older people and the required caregiver support. To inform priorities for future research efforts, different stakeholder perspectives are needed, including those of older people, caregivers, clinicians, and researchers. Objective: To develop a co-designed medication-related research agenda. Methods: A 12-member Advisory Council, half of which were older people and caregivers, designed the research. An 11-question survey to identify priorities for medication-related patient-centered outcomes research (PCOR) topics was administered to members of the Elder Care Medicine Network (ECMN) (ie, older people, caregivers, clinicians, and researchers). Respondents were categorized into two groups with hierarchical assignment to the clinician/research group over the older adult/caregiver group. Chi-square tests compared priority areas for medication-related PCOR between the two groups. Results: There were 53 responses (48% response rate) from the ECMN, with 39.6% (n = 21) from the clinician/researcher group and 60.4% (n = 32) from the older adult/caregiver group. The priority areas from both groups included safe ways to simplify medicines (62.2%), communicating with pharmacists and prescribers about medications (58.5%), and information about safe supplements with prescription medications (52.8%). Statistically significant differences existed between the two groups in the proportions choosing the priority areas. Conclusion: Co-design of a survey to identify priority areas for PCOR demonstrated successful engagement of older people and caregivers as research partners. While older people and caregivers may have differing perspectives on the importance of specific medication-related PCOR topics, simplifying medication regimen and health care communications were germane to both groups.