To ensure optimal patient care based on evidence, it is crucial to understand how to implement new methods in practice. However, intervention studies often overlook parts of the implementation process. A comprehensive process evaluation is necessary to understand why interventions succeed or fail in specific contexts and to integrate new knowledge into daily practice. This evaluation examines the full implementation of the Co-Work-Care model in Swedish primary healthcare to identify strengths and weaknesses. This study aimed to evaluate the process of implementing the CO-WORK-CARE model that focuses on close collaboration and the use of a person-centred dialogue meeting in primary healthcare for patients on sick leave due to common mental disorders. The CO-WORK-CARE model emphasises collaboration among the GP, rehabilitation coordinator and care manager, along with person-centred dialogue meetings involving employers. Following UK Medical Research Council guidelines, we conducted a process evaluation. Data from previous studies were reanalysed. We also analysed field notes and meeting notes using Malterud's qualitative method. The evaluation identified key facilitators for model implementation, including regular visits by facilitators and guidance from the research physician. Peer support meetings also bolstered implementation. However, challenges emerged due to conflicts with existing structures and limitations in person-centred dialogue meetings. Adapting the CO-WORK-CARE model to Swedish primary care is feasible and beneficial, with collaboration among the care manager, rehabilitation coordinator and GP and person-centred dialogue meetings. Thorough preparations, ongoing facilitator and peer support and integrated information enhanced implementation efficiency, despite challenges posed by existing structures.