BACKGROUND: There remain unmet HIV prevention needs in China, particularly among gay, bisexual, and other men who have sex with men. Technology-based interventions are increasingly used in HIV prevention worldwide. OBJECTIVE: We aimed to conduct a systematic review and meta-analysis of studies to assess the effectiveness of technology-based HIV prevention interventions to improve HIV testing and consistent condom use in China. METHODS: We searched English-language (PubMed and MEDLINE, Embase, and Web of Science) and Chinese-language (Wanfang, WEIPU, and China National Knowledge Infrastructure) databases for technology-based HIV prevention intervention studies published between January 1, 2004, and September 30, 2021. Eligible studies were technology-based HIV prevention intervention studies with outcomes of HIV testing or condom use among men who have sex with men or transgender women using randomized controlled or nonrandomized pretest-posttest designs in China. The intervention technologies identified were apps, web pages, and other types of electronic communications (eg, email, SMS text messages, and video messages). A Bayesian meta-analysis was conducted to estimate the pooled effect size and 95% credible interval (CrI). We added study and intervention features as covariates to explore their associations with the study effects. Study quality was assessed using the integrated quality criteria for review of multiple study designs. Publication bias was assessed using funnel plots and robust Bayesian meta-analyses. RESULTS: We identified 1214 and 1691 records from English-language and Chinese-language databases, respectively. A total of 141 records entered full-text screening, and 24 (17%) studies were eligible for the review. Approximately half (14/24, 58%) of the interventions were delivered through social media platforms, predominantly using message-based communication. The remaining studies used email and web-based platforms. The pooled effect sizes estimated were an absolute increase of 20% (95% CrI 10%-30%) in HIV testing uptake and an absolute increase of 15% (95% CrI 5%-26%) in consistent condom use. The pooled point estimate of the effect of randomized controlled trials was smaller than that of nonrandomized studies for HIV testing uptake (16% vs 23%) and consistent condom use (10% vs 19%), but their CrIs largely overlapped. Interventions lasting >6 months were associated with a 35% greater uptake of HIV testing (95% CrI 19%-51%) compared to those lasting 6 months. CONCLUSIONS: Technology-based HIV prevention interventions are promising strategies to improve HIV testing uptake and consistent condom use among men who have sex with men in China, with significant effects found across a broad array of studies and study designs. However, many studies in this review did not include randomized designs or a control group. More rigorous study designs, such as randomized controlled trials, are needed, with outcome measurements that address the limitation of self-report outcomes to inform the development and implementation of future intervention programs. TRIAL REGISTRATION: PROSPERO CRD42021270856; https://www.crd.york.ac.uk/PROSPERO/view/CRD42021270856.