Background Chronic leg ulcers affect 1-3% of the population and are costly to treat and health service resource intensive. Venous aetiology contributes to about 70% of all chronic leg ulcers; these ulcers are often associated with prolonged ill health, pain and decreased physical functioning, and have a substantial impact on health-related quality of life.Aim The primary aim of this systematic review is to identify literature on the risk factors for delayed healing or non-healing of venous leg ulcers (VLUs) in adults.Methods This systematic review will be guided by the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) 2015 statement. Studies will be identified from PubMed, ScienceDirect, Web of Science, ProQuest, CINAHL Complete, MEDLINE, APA PsychINFO, Academic Search Elite, Cochrane Library, JBI EPD (evidence-based practice database), ProQuest (Dissertations and Theses Global) and Global ETD (electronic theses and dissertations) Search Engine up to August 2021. Methodological quality will be assessed using the Mixed Methods Appraisal Tool (MMAT) 2018. A narrative synthesis of risk factors will be categorised as physiological (general/medical), clinical, demographics or psychosocial.