OBJECTIVES: To estimate the prevalence of influenza coinfection in COVID-19 patients and investigate its association with severe clinical outcomes. METHODS: We systematically searched the Web of Science, PubMed, Scopus, Embase, The Cochrane Library, and CNKI for studies published between January 01, 2020, and May 31, 2023. Meta-analysis was performed to estimate the pooled prevalence of coinfection and the impact on clinical outcomes. Systematic review registered in PROSPERO (CRD42023423113). RESULTS: A total of 95 studies involving 62,107 COVID-19 patients were included. The pooled prevalence of coinfection with influenza virus was 2.45% (95% confidence interval [CI]: 1.67-3.58%), with a high proportion of influenza A. Compared with mono-infected patients (COVID-19 only), the odds ratio (OR) for severe outcomes (including intensive care unit admission [OR = 2.20, 95% CI: 1.68-2.87, P < 0.001], mechanical ventilation support [OR = 2.73, 95% CI: 1.46-5.10, P = 0.002], and mortality [OR = 2.92, 95% CI: 1.16-7.30, P = 0.022]) was significantly higher among patients coinfected influenza A. CONCLUSION: Although the prevalence of coinfection is low, coinfected patients are at higher risk of severe outcomes. Enhanced identification of both viruses, as well as individualized treatment protocols for coinfection, are recommended to reduce the occurrence of serious disease outcomes in the future.