BACKGROUND: This study systematically analysed global and regional adherence to mask-wearing and its impact on the incidence and deaths of viral respiratory infectious diseases (VRIDs). METHODS: Relevant studies were sourced from PubMed, Web of Science, Embase and Scopus. We included observational studies with available raw data on mask-wearing adherence (rates of acceptability of mask-wearing, mask-wearing in public settings and correct mask-wearing) during VRID pandemics/epidemics. The COVID-19-related incidence and deaths were sourced from Global Burden of Diseases 2021. The quality of each study was assessed using the Agency for Healthcare Research and Quality Scale. Pooled rates and effects of mask-wearing were calculated using random effects models and generalised linear models. RESULTS: We included 448 studies from 70 countries/regions. During the VRID pandemics/epidemics, global pooled rates for the acceptability of mask-wearing, mask-wearing in public settings and correct mask-wearing were 65.27% (95% CI 60.34% to 70.05%), 74.67% (95% CI 69.17% to 79.8%) and 63.63% (95% CI 59.28% to 67.87%), respectively. In individuals with chronic diseases/elderly/pregnant women, the rates of acceptability (42.54%) and correct mask-wearing (60.56%) were both low. Among the general population, the rates of mask-wearing in public settings (68.2%) and correct mask-wearing (57.45%) were the lowest. During the COVID-19 pandemic, countries with a requirement for mask-wearing exhibited a higher rate in public settings (76.10% vs 58.32%), especially in regions with more stringent containment and health measures (β=0.86, p=0.008). The mask-wearing in public settings has been found to significantly reduce the COVID-19 incidence (β=-265.26, p=0.004), COVID-19 deaths (β=-2.04, p<
0.001) and other COVID-19 pandemic-related deaths (β=-0.83, p<
0.001). CONCLUSION: During the VRID pandemics/epidemics, adherence to mask-wearing was relatively low. Implementing policies requiring mask-wearing during the pandemic could enhance the mask-wearing rate, potentially leading to a significant reduction in VRID-related incidence and deaths. TRIAL REGISTRATION NUMBER: CRD42024496464.