Contraceptive stock-outs are a world-wide problem, yet published research on the impacts of contraceptive stock-outs have not been comprehensively reviewed and synthesised. This systematic review highlights findings about the impacts of contraceptive stock-outs on users, providers, and facilities and identifies topics that should be explored to ensure everyone can access their preferred method of contraception. We systematically searched PubMed, Embase, Web of Science, Popline, and JSTOR for studies addressing the impacts of contraceptive stock-outs. Of 435 studies, 25 publications addressed the impacts of contraceptive stock-outs. Only two articles focused solely on contraceptive stock-outs; the remaining studies examined stock-outs alongside other factors that may influence contraceptive service provision. Studies discussed how stock-outs limited individuals' ability to use their preferred contraceptive method, influenced where contraceptive methods were obtained and how much they cost, and limited providers' and facilities' abilities to provide contraceptive care. Comparing the impacts of contraceptive stock-outs across studies was challenging, as reliability of stock was sometimes not distinguished from overall method availability, and studies used variable methods to measure stock-outs. Evidence presented in this review can inform efforts to ensure that preferred contraceptive methods are consistently available and accessible to all.