Background <p>Breast cancer is China’s top threat to women’s health, causing physical and emotional distress that affects sleep and recovery outlook.</p> Objective <p>To investigate the effect of family resilience on sleep quality and hope level in patients undergoing radical mastectomy for breast cancer.</p> Methods <p>A cross-sectional survey was conducted among 200 patients who underwent modified radical mastectomy in the breast surgery department. The self-made general information questionnaire, Family Resilience Questionnaire (FaRE), Pittsburgh Sleep Quality Index (PSQI), and Herth Hope Scale (HHI) were used to investigate their family resilience, sleep quality, and hope level. At the same time, the Spearman correlation was used to analyze the relationship between family resilience, sleep quality, and hope level. The mediating role of family resilience on sleep and hope was analyzed using stepwise regression and validated with the bootstrap method.</p> Result <p>Finally, 185 valid questionnaires were collected. The FaRE score of 185 patients after modified radical mastectomy was (101.32 ± 17.98), the PSQI score was (7.58 ± 2.03), and the HHI score was (35.30 ± 5.43). Family resilience was negatively correlated with sleep quality (<i>r</i> = − 0.497, <i>P</i> &lt; 0.001) and positively correlated with hope level (<i>r</i> = 0.551, <i>P</i> &lt; 0.001). Sleep quality was negatively correlated with hope level (<i>r</i> = − 0.405, <i>P</i> &lt; 0.001). Family resilience played a partial mediating role between sleep quality and hope level, with a mediating effect of 53.11%.</p> Conclusions <p>Family resilience can indirectly affect the hope level of patients by regulating their sleep quality.</p>