Introduction: Moral injury involves the adverse psychological, biological, spiritual, behavioural, and social consequences of actions that violate moral values. It can lead to anxiety, depression, burnout, and post-traumatic stress disorder. Nurses, who often face ethical dilemmas, are particularly vulnerable. Despite its significance, the relationship between moral injury and mental health outcomes in nurses remains underexplored. Aim: This systematic review aimed to describe the associations among moral injury, anxiety, depression, and quality of life in nurses. Methods: The review was registered in (...) PROSPERO (CRD42023438731) and was conducted following the PRISMA guidelines. A literature search was performed in December 2023 across PubMed, CINAHL, Scopus, and Web of Science. Peer-reviewed primary research involving nurses, published in English or Italian, without time restrictions, was considered eligible. The risk of bias and the quality of evidence were assessed using the Joanna Briggs Institute checklist and the GRADE approach. Results: Out of 4730 articles identified, eight met the inclusion criteria. The analysis revealed significant positive associations between moral injury, anxiety, and depression, along with a significant negative association with quality of life. Conclusion: These findings highlight the need for healthcare systems to implement strategies that mitigate moral injury among nurses. Future research should prioritize longitudinal studies to explore causal relationships and develop targeted interventions. Additionally, standardizing the concept and measurements of moral injury is crucial for enhancing the comparability and understanding of this phenomenon. (shrink)