Objective To assess the global situation of off-label drug use in hospitalized children. Methods The databases such as PubMed, EMbase, CBM, CNKI and VIP were searched to collect studies on off-label drug use in hospitalized children at age of 0 to 18 years old. The publication language was limited to English and Chinese. The quality assessment was based on Crombie Criteria for cross-sectional studies. The incidence of off-label drug use was described in different wards and age groups, and the proportion of different off-label used drugs was analyzed. Results The total 29 cross-sectional studies were included, involving 8 560 children and 41 655 prescriptions. a) Median (IQR) of off-label use incidence: Neonatal ICU 52.5% (23.0% to 44.8%), Pediatric ICU 43.5% (34.5% to 60%), General pediatric ward 35.5% (23.8% to 43.3%), Pediatric surgical ward 27.5% (23.0% to 44.8%); b) The results of off-label incidence in different age groups were inconsistent among different studies; and c) The off-label drug use for “no pediatric information” had the largest proportion, followed by dose and age. Conclusion a) Off-label drug use exists widely around the world, but the incidence varies a lot in different countries and different types of wards; b) The incidence of off-label drug use may be higher in ICU than in non-ICU, and higher in the neonatal ward than the pediatric ward; c) The off-label drug use for no pediatric information is the commonest type, and further clinical studies should focus on areas in which high quality evidence is totally absent; and d) The multi-center studies with unified design on off-label drug use in hospitalized children in China are urgently needed to provide evidence for policy-making.