BackgroundPeople with dementia often do not receive optimal person‐centred care (PCC) in care settings. Family members can play a vital role as care partners to support the person with dementia with their psychosocial needs. Participatory research that includes the perspectives of those with lived experience is essential for developing high‐quality dementia care and practices.ObjectiveThroughout 2021–2022, a mobile app, called WhatMatters, was co‐developed to provide easy‐to‐access and personalised support for people with dementia in hospitals and long‐term care homes, with input from patients/residents, family partners and healthcare staff. This article discusses and critically reflects on the experiences of patients/residents, family partners, and healthcare staff involved in the co‐design process.MethodsFor the app development, we applied a participatory co‐design approach, guided by a User Experience (UX) model. The process involved co‐design workshops and user testing sessions with users (patients/residents, family partners, healthcare staff) to co‐develop the WhatMatters prototype. We also conducted focus groups and one on one interviews with staff and caregiver participants to explore their experiences. Our research team, which also included patient partners, took part in regular team meetings during the app's development, where we discussed and reflected on the co‐design process. Reflexive thematic analysis was performed to identify themes that represent the challenges and rewarding experiences of the users involved in the co‐design process, which guided our overall reflective process.FindingsOur reflective analysis identified five themes (1) clarifying the co‐design process, (2) ensuring inclusive collaborations of various users, and (3) supporting expression of emotion in a virtual environment, (4) feeling a sense of achievement and (5) feeling valued.ImplicationsWhatMatters offers potential for providing personally relevant and engaging resources in dementia care. Including the voices of relevant users is crucial to ensure meaningful benefits for patients/residents. We offer insights and lessons learned about the co‐design process, and explore the challenges of involving people with lived experiences of dementia in co‐design work, particularly during the pandemic.