This review examined relationships between nurse unit managers' leadership and patient safety and quality of care outcomes in hospital settings. Employing four databases (CINAHL, Embase, PubMed, and Web of Science) and ancestry searches, we identified 14 English-language, peer-reviewed, primary studies that examined such relationships using quantitative analyses. The studies were published between 2012 and 2021, and most used a cross-sectional design. Each study's quality was assessed using the Mixed-Method Appraisal Tool. In synthesizing results by categorizing outcomes, we found a positive trend in associations between effective nurse unit manager leadership and better outcomes, including fewer patient adverse events, increased nurse error reporting, and higher patient satisfaction and care quality. However, the heterogeneity of leadership measurement approaches and outcomes limited integration of study findings. Future researchers should clearly define study concepts to support interpretation of their findings and should use a suitable theoretical framework to help determine appropriate units of analysis.