BackgroundChildhood hypertension is an important global public health issue, but prevalence estimates remain inconsistent. To date, no meta-analysis has synthesised global prevalence using both in-office blood pressure measurements and combined in-office and out-of-office assessments. We aimed to provide updated global prevalence estimates of childhood hypertension using both diagnostic approaches.MethodsIn this systematic review and analysis, we searched PubMed, Embase, and MEDLINE for population-based studies published between Jan 1, 2000, and April 19, 2025, reporting the prevalence of hypertension in the general paediatric population aged 19 years or younger. This was supplemented by eligible studies identified from relevant systematic reviews and manual reference screening. Two reviewers independently screened records for eligibility, extracted study-level data, and assessed the risk of bias. Random-effects meta-analysis was used to estimate pooled prevalence. Subgroup analyses were performed by age, sex, setting (urban vs rural), device, investigation period, BMI group, and WHO and World Bank regions. Meta-regression was performed to examine age-specific prevalence, sex-specific prevalence, and secular trends. Primary outcomes were the prevalence of childhood hypertension assessed using repeated in-office blood pressure measurements based on at least three separate occasions (in-office approach) and a combination of in-office and out-of-office blood pressure measurements (combination approach). This study was registered with PROSPERO, CRD420251057655.FindingsWe identified 11 703 records from database searches, supplemented by 87 articles retrieved from relevant systematic reviews and manual reference screening. Ultimately, 96 articles met the inclusion criteria, all of which were rated with quality scores of at least 5. For the in-office approach, 83 articles included a total of 443 914 children and adolescents across 21 countries. Based on 81 articles, the pooled prevalence of childhood hypertension was 4·28% (95% CI 3·71-4·90). Prevalence increased with age, peaking at 14 years before declining. Between 2000 and 2020, the prevalence of childhood hypertension nearly doubled, increasing from 3·40% (95% CI 2·14-5·34) to 6·53% (4·17-10·07) in boys and from 3·02% (1·90-4·75) to 5·82% (3·71-9·01) in girls. Regarding the combination approach, 15 articles included 12 597 children and adolescents across nine countries. The pooled prevalence was 6·67% (95% CI 1·66-14·53) for sustained hypertension based on five articles.InterpretationChildhood hypertension affects a substantial and growing proportion of the global paediatric population, with prevalence varying considerably by diagnostic approach. These findings underscore the need for harmonised diagnostic criteria in paediatric hypertension research.FundingNational Natural Science Foundation of China.