Background WHO estimates that seasonal influenza epidemics result in three to five million cases of severe illness (hospitalisations) every year. We aimed to improve the understanding of influenza-associated hospitalisation estimates at a national and global level.Methods We performed a systematic literature review of English-and Chi-nese-language studies published between 1995 and 2020 estimating influen-za-associated hospitalisation. We included a total of 127 studies (seven in Chi-nese) in the meta-analysis and analyzed their data using a logit-logistic regression model to understand the influence of five study factors and produce national and global estimates by age groups. The five study factors assessed were: 1) the method used to calculate the influenza-associated hospitalisation estimates (rate-or time series regression-based), 2) the outcome measure (divided into three en-velopes: narrow, medium, or wide), 3) whether every case was laboratory-con-firmed or not, 4) whether the estimates were national or sub-national, 5) whether the rates were based on a single year or multiple years.Results The overall pooled influenza-associated hospitalisation rate was 40.1 (95% confidence interval (CI) = 23.3-69.1) per 100 000 persons, with rates vary-ing substantially by age: 137.8 (95% CI = 70.6-268.7) in children aged 0-4 years and 71.6 (95% CI = 39.9-127.7) in the elderly aged >65 years. The overall pooled hospitalisation rates varied by calculation method; for all ages, the rates were sig-nificantly higher when they were based on rate-based methods or calculated on a single season and significantly lower when cases were laboratory-confirmed. The national hospitalisation rates (all ages) varied considerably, ranging from 11.7 (95% CI = 3.8-36.3) per 100 000 in New Zealand to 122.1 (95% CI = 41.5-358.4) per 100 000 in India (all age estimates).Conclusions Using the pooled global influenza-associated hospitalisation rate, we estimate that seasonal influenza epidemics result in 3.2 million cases of se-vere illness (hospitalisations) per annum. More extensive analyses are required to assess the influence of other factors on the estimates (e.g. vaccination and dom-inant virus (sub)types) and efforts to harmonize the methods should be encour-aged. Our study highlights the high rates of influenza-associated hospitalisations in children aged 0-4 years and the elderly aged 65+ years.