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Introduction In 2002, hepatitis B vaccines were incorporated into China’s National Immunisation Programme (NIP). In 2009, the catch-up vaccination was introduced for children born between 1994 and 2001. Sustained impacts of the NIP, particularly the catch-up vaccination, remain unclear. We aimed to evaluate the effectiveness of the NIP and catch-up vaccination on the incidence of hepatitis B in China.Methods We collected monthly reported hepatitis B cases in 31 provincial-level administrative districts (PLAD) in China from 2005 to 2019. Using two-stage generalised additive models with the interrupted time series design, we first estimated the effectiveness of the NIP and catch-up vaccination on hepatitis B incidence in each of the nine age groups within the study population, aged 5–29 years in each PLAD. Then, we used random-effects models to pool the effectiveness estimates for the same age group across PLADs and calculated the age-standardised population-weighted national effectiveness.Results Reported hepatitis B cases amounted to 4 452 376 in China among the study population. Compared with the pre-NIP period, the NIP contributed to an average decrease of 54.82% (95% CI 36.39% to 67.33%) in the incidence among individuals aged 5–19 years. Among individuals aged 9–29 years, the incidence associated with the catch-up vaccination decreased by 54.50% (95% CI 48.49% to 59.60%) on average. The NIP and catch-up vaccination could prevent an average of 24.66 (95% empirical CI (eCI) 13.74 to 25.01) and 25.69 (95% eCI 23.91 to 26.99) cases per 100 000 individuals annually, respectively. Interventions were notably more effective in northwest China and in PLADs with lower HBsAg prevalence, low hospitalisation bed density, low urbanisation rates or low illiteracy rates, reducing disparities in the burden of hepatitis B.Conclusions The NIP and the catch-up vaccination initiative significantly reduced hepatitis B incidence across China. These findings have important implications for optimising existing national or international hepatitis B-related vaccination strategies.