INTRODUCTION: Endometriosis is a chronic disease associated with substantial impairment in health-related quality of life (HRQoL) and considerable financial burden. This study aimed to examine how patient-reported financial toxicity and disease acceptance are associated with HRQoL in women with endometriosis and to assess the potential mediating role of disease acceptance in this relationship. METHODS: This cross-sectional study included 411 women with endometriosis recruited in Poland through online patient communities, social media channels, endometriosis-related networks, and a collaborating Women's Health Center. Patient-reported financial toxicity, disease acceptance, and HRQoL were assessed using the COST-FACIT, Acceptance of Illness Scale (AIS), and Endometriosis Health Profile-30 (EHP-30), respectively. The potential mediating role of disease acceptance in the association between financial toxicity and HRQoL was examined using regression-based mediation analysis with 5,000 bootstrap samples, adjusting for age, household income, previous surgical treatment, and infertility treatment. RESULTS: Higher COST-FACIT scores, indicating lower financial toxicity, were associated with greater disease acceptance [B = 0.618, 95% CI (0.552; 0.683), p < 0.001] and better HRQoL [B = -0.537, 95% CI (-0.711; -0.362), p < 0.001]. Greater disease acceptance was also associated with better HRQoL [B = -0.963, 95% CI (-1.144; -0.784), p < 0.001]. Mediation analysis showed a statistically significant indirect association between financial toxicity and HRQoL through disease acceptance [B = -0.595, 95% CI (-0.731; -0.472)], while the direct association remained statistically significant. Older age and previous infertility treatment were independently associated with better HRQoL (lower EHP-30 scores), whereas household income and previous surgical treatment were not. CONCLUSION: Patient-reported financial toxicity was associated with both disease acceptance and HRQoL in women with endometriosis. The observed indirect association through disease acceptance is consistent with the possibility that psychological adaptation may represent one component of the relationship between financial toxicity and HRQoL. however, the cross-sectional design does not allow the temporal ordering or causality of these associations to be established. These findings support considering financial well-being alongside psychological factors when evaluating the broader impact of endometriosis on patients' quality of life.