ABSTRACT Objective Rumination is a common cognitive response in cancer patients, influencing psychological adjustment. This study examined the associations between intrusive and deliberate rumination and self‐compassion in individuals undergoing cancer treatment, using structural equation modeling (SEM). Methods A cross‐sectional correlational study was conducted with 202 adult cancer patients undergoing active treatment at a public hospital. Participants completed validated self‐report instruments: the Event‐Related Rumination Inventory and the Brief Self‐Compassion Inventory. Data were analyzed using descriptive statistics, Pearson correlation, and SEM. Results The SEM results indicated that intrusive rumination was significantly and negatively associated with self‐compassion ( β = −0.828, p < 0.001), whereas deliberate rumination showed a significant positive association with self‐compassion ( β = 0.753, p < 0.001). The model explained 60.3% of the variance in self‐compassion. Subgroup analyses showed that self‐compassion and deliberate rumination were higher among participants with higher education and those who were employed, while intrusive rumination was higher in patients with prior metastasis or relapse. Conclusions The findings underscore the need to distinguish between adaptive and maladaptive forms of rumination in cancer care. Targeting intrusive rumination and supporting deliberate reflection may represent important considerations for psychosocial care.