Introduction: The treatment gap in mental health services in Indonesia is a critical issue driven by the shortage of professionals, challenging geography, limited medication availability, and stigma around mental health. Despite having limited access and facilities, Dum Primary Care in the District of Sorong Islands is the only primary care that provides mental health services to the community. This study aims to explore community-based mental health promotion using the theory of planned behavior. Methods: This study used qualitative research consist of three stages: developing interview guidelines, which were piloted with local health workers; semi-structured (SSIs) interviews; and focus group discussions (FGDs). A total of 11 participants were engaged in the study, including six professionals, two patients, and three caregivers. Results: Behavioral beliefs influence patients' intentions to recover and seek treatment independently. In subjective norms, patients with mental illness face contrasting family attitudes toward treatment, including support and rejection. Perceived control factors affecting mental health promotion in the community include family socioeconomic status, limited access to care, stigma, and inadequate government funding. The knowledge and skills of health workers are also vital for effectively reaching and supporting patients in promoting mental health. Conclusion: Enhancing collaboration between families and primary care is vital in promoting mental health. By actively engaging families and communities, primary care can improve mental health literacy and reduce the stigma associated with mental health issues. Implementing mental health lay workers can help address the shortage of professionals and improve service delivery in the community.