Purpose <p>Breast cancer is the most common cancer among women in Iraq, and chemotherapy often leads to sleep disturbances and emotional strain. Emotional resilience may help patients cope with these challenges. Therefore, this study aimed to examine the relationship between sleep quality and emotional resilience among breast cancer patients undergoing chemotherapy in Iraq.</p> Methods <p>This cross-sectional study was conducted from August 1st, 2024, to February 13th, 2025, in five major public hospitals across Iraq, using purposive sampling. Data were collected using a structured questionnaire consisting of sociodemographic information, the Pittsburgh Sleep Quality Index (PSQI), and the Adult Resilience Measure–Revised (ARM-R). Statistical analysis was performed using Stata version 12 (StataCorp LLC, College Station, TX).</p> Results <p>In the study, 433 breast cancer patients were involved. The findings indicated that, on average, participants stated poor sleep quality. They exhibited a high degree of emotional resilience. The analysis showed a significant negative correlation between sleep quality and resilience, suggesting that higher resilience correlates with improved sleep quality. Further multiple linear regression analysis indicated that higher resilience was associated with better sleep quality. Furthermore, age was negatively associated with sleep quality, suggesting that older patients slept slightly better, while physical complications were positively associated with poor sleep quality.</p> Conclusions <p>The study revealed a significant negative correlation between sleep quality and emotional resilience among breast cancer patients undergoing chemotherapy in Iraq. Policymakers and healthcare providers are recommended to integrate psychosocial support and resilience-building interventions into oncology care to improve sleep quality and overall wellbeing in this vulnerable population.</p>