Objective Adolescents and young adults (AYA) with HIV are a population at high risk of experiencing mental issues and sleep disorder. We aim to summarise the global prevalence and risks of depression, anxiety, post-traumatic stress disorder (PTSD) and sleep disorder among AYA with HIV.Design Systematic review and meta-analysis.Data sources PubMed, Web of Science, Embase and PsycINFO were searched from inception to 3 August 2024.Eligibility criteria Observational studies reporting the prevalence of depression, anxiety, PTSD or sleep disorder among AYA with HIV and published in English were included. Reviews, case reports, conference papers, notes, editorials and non-observational research were excluded.Data extraction and synthesis Titles, abstracts and full texts were reviewed and screened, and data were independently extracted. A modified Newcastle-Ottawa Quality Assessment Scale (NOS) was used to evaluate study quality. Heterogeneity was assessed by I2 statistics, and subgroup analysis was performed to identify the source of heterogeneity. The pooled prevalence and the risks of depression, anxiety, PTSD and sleep disorder by comparison with HIV-uninfected peers were measured with random-effects and fixed-effects models. Publication bias was examined using Egger’s correlation tests and funnel plot. The Grading of Recommendations Assessment, Development and Evaluation was used to assess the certainty of evidence.Results 56 articles were included in the final analysis. According to the modified NOS, 13 (23.2%) studies were considered good, 38 (67.9%) were satisfactory and 5 (8.9%) were unsatisfactory. 51 studies including 21 735 AYA with HIV contributed data for the pooled prevalence of depression (28%, 95% CI 24% to 32%, I2=98.68%; low certainty evidence); 21 studies including 8021 cases contributed data for the pooled prevalence of anxiety (22%, 95% CI 17% to 27%, I2=98.35%; low certainty evidence); 9 studies including 3691 cases contributed data for the pooled prevalence of PTSD (12%, 95% CI 8% to 17%, I2=95.60%; low certainty evidence); and 4 studies including 1909 cases contributed data for the pooled prevalence of sleep disorder (51%, 95% CI 31% to 70%, I2=98.37%; low certainty evidence). Compared with AYA without HIV, those with HIV had a higher risk of depression (OR=2.67, 95% CI 1.63 to 5.90, I2=84.0%), anxiety (OR=1.89, 95% CI 1.32 to 2.69, I2=50.3%), PTSD (OR=1.58, 95% CI 1.23 to 2.04, I2=40.1%) and sleep disorder (OR=2.11, 95% CI 1.51 to 2.95, I2=0.0%). A subgroup analysis found that studies conducted in Asia had a lower prevalence of depression (21.7% vs 29.6%, p