PURPOSE: Breast cancer is a prevalent and emotionally challenging condition that profoundly affects women worldwide. Effectively managing the mental and emotional dimensions of this disease is crucial for the holistic well-being of patients. Psychological capital (PsyCap) has emerged as a pivotal psychological construct with the potential to effectively address these challenges. This study aims to explore the influential role of PsyCap and its constructs on the subjective well-being (SWB) of Iranian breast cancer patients. METHODS: A total of 173 breast cancer patients participated in this study, selected through a random sampling approach. Face-to-face interview data on socio-demographics, PsyCap, and SWB were collected using a structured questionnaire. The analytical procedures encompassed independent sample RESULTS: The findings revealed that the majority of participants fell within the 41-50 age group (38.7%), with an average age of 46.50 ± 11.76 years, and 35.8% had tumor growth in the upper left lobe. The average PsyCap score was 107.93 ± 1.52 (out of a possible score of 144), whereas SWB scored 196.51 ± 1.90 (out of 291). Notably, PsyCap showed a positive correlation with SWB ( CONCLUSIONS: Focusing on understanding and addressing factors like PsyCap, self-efficacy, and educational support could improve SWB, offering a potential avenue for comprehensive and individualized psychosocial care for women with breast cancer.