Overweight and obesity are common in school-age children. Policy, system, and environmental (PSE) approaches--which entail making upstream changes to a school's context--can be leveraged to reduce childhood obesity. Nurses can advance PSE approaches in schools to promote healthy living habits. This review examines the effect of nurse-involved PSE interventions globally to promote healthy nutrition and reduce obesity in schools. We conducted a literature search using multiple databases from 2010 to 2023 for nurse-involved studies that implemented interventions focused on PSE change related to promoting healthy nutrition or reducing obesity in school settings. Twenty interventions globally were included in the systematic review synthesis. Improvements in anthropometrics, health and nutrition knowledge, attitudes, and beliefs were observed. PSE interventions can be leveraged to promote healthy nutrition and reduce obesity in school settings. Nurses in varying roles are uniquely qualified to advocate for and implement school-based interventions focused on PSE change.