BACKGROUND: Reducing involuntary psychiatric admissions is a global concern. In Norway, the rate of involuntary admissions was 199 per 100,000 people 16 years and older in 2020. Individuals' paths towards involuntary psychiatric admissions usually unfold when they live in the community and referrals to such admissions are often initiated by primary health care professionals. Interventions at the primary health care level can therefore have the potential to prevent such admissions. Interventions developed specifically for this care level are, however, lacking. To enhance the quality and development of services in a way that meets stakeholders' needs and facilitates implementation to practice, involving both persons with lived experience and service providers in developing such interventions is requested. AIM: To develop a comprehensive intervention for primary mental health care aiming to prevent involuntary admissions of adults. METHODS: This study had an action research approach with a participatory research design. Dialogue conferences with multiple stakeholders in five Norwegian municipalities, inductive thematic analysis of data material from the conferences, and a series of feedback meetings were conducted. RESULTS: The co-creation process resulted in the development of the ReCoN (Reducing Coercion in Norway) intervention. This is a comprehensive intervention that includes six strategy areas: [1] Management, [2] Involving Persons with Lived Experience and Family Carers, [3] Competence Development, [4] Collaboration across Primary and Specialist Care Levels, [5] Collaboration within the Primary Care Level, and [6] Tailoring Individual Services. Each strategy area has two to four action areas with specified measures that constitute the practical actions or tasks that are believed to collectively impact the need for involuntary admissions. CONCLUSIONS: The ReCoN intervention has the potential for application to both national and international mental health services. The co-creation process with the full range of stakeholders ensures face validity, acceptability, and relevance. The effectiveness of the ReCoN intervention is currently being tested in a cluster randomised controlled trial. Given positive effects, the ReCoN intervention may impact individuals with a severe mental illness at risk of involuntary admissions, as more people may experience empowerment and autonomy instead of coercion in their recovery process.