Background <p>This study aims to assess the level of ethical distress experienced by intensive care unit (ICU) nurses in their work, thereby providing a theoretical basis for the development of evidence-based interventions.</p> Methods <p>The review was registered in PROSPERO (CRD42025637436) and was conducted following the PRISMA guidelines. A comprehensive search was conducted across multiple databases, including PubMed, Embase, the Cochrane Library, Web of Science, and ClinicalTrials.gov, to identify original studies published up to January 2025 that explore the experiences of moral distress among ICU nurses. The methodological quality of the included studies was rigorously assessed using the 2018 version of the Mixed Methods Appraisal Tool (MMAT).</p> Results <p>This systematic review encompasses a total of 34 articles, involving 6,461 participants from 13 countries. The results showed that the weighted mean difference (WMD) based on the revised Moral Distress Scale (MDS-R) score was 49.98 (95% CI 38.02–61.94, <i>p</i> &lt; 0.001), and the Measure of Moral Distress for Healthcare Professionals (MMD-HP) score was 88.32 (weighted MD [WMD] 88.32, 95% CI 54.13–122.51, <i>p</i> &lt; 0.001), indicating that ICU nurses are experiencing moderate levels of moral distress. Subgroup analysis of MDS-R scores by gender did not show significant differences (MD 3.49, 95% CI 5.74–12.72, <i>p</i> = 0.46, I² = 62%), indicating no association between the intensity of moral distress among ICU nurses and gender.</p> Conclusion <p>ICU nurses are experiencing moderate moral distress. Nursing administrators should prioritize the distressing experiences induced by moral distress among ICU nurses and adopt a multifaceted intervention strategy to proactively address these challenges, thereby mitigating the intensity of moral distress faced by ICU nurses and enhancing the quality of nursing care services.</p> Clinical trial number <p>Not applicable.</p>