Aim: The aim of this study was to substantiate the perceptions and experiences of nursing students related to nurse understaffing in the clinical learning environment. Background: The quality of the clinical learning environment affects students' learning experiences, shapes their thinking about the profession and can influence their choice to stay or leave the profession. Understaffing in the clinical learning environment has an adverse impact on patient safety, quality of care outcomes and mortality. Understaffing has an impact on students' learning by reducing the quality of supervision and mentoring. Design: A systematic narrative review. Methods: Databases of Academic Search Premier, MEDLINE, Psychology and Behavioural Sciences, APA PsycINFO, APA PsycArticles, CINAHL, AMED were searched systematically. The review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The reviewers independently conducted study selection, quality appraisal and data extraction. Quality appraisal was performed using the Mixed Methods Appraisal Tool (MMAT). Thematic analysis was used to synthesise the findings. Results: A total of eight research papers were included. Four themes were identified: inadequate support, feeling unprotected, being seen as a cover for staff shortages on shifts and patients ultimately suffer the consequences of understaffing. Conclusions: This review revealed that understaffing in the learning environment meant that optimum level of supervision could not be provided, making students feel vulnerable and insecure, students felt unwelcome and used as cover for staff shortages. We recommend further examination of understaffing to inform policy for improvement in student-staff ratio, supervision and facilitation of learning.