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.