Background: Diabetes Mellitus (DM) has been one of the major global health problems in the last few decades and one of four priority non-communicable diseases targeted for action by world leaders, according to World Health Organization. In Oman, DM is currently considered the sixth leading cause of mortality and the fifth most prominent cause of disability. Patients with DM are constantly confronted with the disease's stressful demands and utilize various strategies to manage it. Self-Management, dependent on the patient's initiative, is a critical component of treatment, and it has been linked to the patient's psychological and social circumstances. Studies examining the association between resilience, social support, coping, and Diabetes Self-Management (DSM) are lacking in Oman. Purpose: The study examined the psychosocial factors (i.e., resilience, social support, and coping) associated with self-management among adult patients with DM residing in Oman. Methods: A descriptive cross-sectional, correlational study examines the relationship between resilience, social support, and coping with self-management in adult patients with DM. This study included 212 DM patients from Bousher Specialized Polyclinic, Al-Seeb Specialized Polyclinic, and Sultan Qaboos University Hospital in Oman. Data were collected using four main instruments (i.e., Diabetes Self-Management Questionnaire-Revised, Conner & Davison Resilience Scale, Medical Outcome Study Social Support Survey, and The Brief COPE Inventory). Results: The mean age of the participants was 34 years old (SD = 12.1). The majority of the participants (63.7%) of the participants were type 1 DM, whereas 36.3% of them had type 2 DM. The mean DM duration was 10.6 years (SD=6.74). The mean HbA1C result is 8.8% (SD=2.31). The study's findings showed participants had optimal DSM (mean=6.32). The relationship between resilience, social support, and coping with self-management in patients with DM was statistically significant (p 0.05). In addition, the Sobel test found a statistically significant relationship between coping as a mediator between resilience, social support, and self-management (p = 0.000). Moreover, the stepwise regression model was statistically significant with four predictors of DSM (i.e., coping, type of DM, income, and age). Conclusion: This study provides an understanding of the level of DSM among Omani patients and the factors associated with better adherence to DSM. The findings showed that patients had optimal DSM associated significantly with resilience, social support, and coping. A better understanding of these factors and their contribution to enhancing self-management may improve health outcomes, increase the quality of life, and reduce DM complications. It will guide stakeholders, including healthcare professionals, educators, psychologists, researchers, and policymakers, to design and implement the strategies that improve DSM among DM people in Oman.