Background: High-risk gestational trophoblastic neoplasia (GTN) is rare and treated with diverse approaches. Limited published institutional data has yet to be systematically reviewed. Objectives: To compile global high-risk GTN (prognostic score ≥7) cohorts to summarise treatments and outcomes by disease characteristics and primary chemotherapy. Search Strategy: MEDLINE, Embase, Scopus, ClinicalTrials.gov and Cochrane were searched through March 2021. Selection Criteria: Full-text manuscripts reporting mortality among ≥10 high-risk GTN patients. Data Collection and Analysis: Binomial proportions were summed, and randomeffects meta-analyses performed. Main Results: From 1137 records, we included 35 studies, representing 20 countries. Among 2276 unique high-risk GTN patients, 99.7% received chemotherapy, 35.8% surgery and 4.9% radiation. Mortality was 10.9% (243/2236; meta-analysis: 10%, 95% confidence interval [CI] 7-12%) and likelihood of complete response to primary chemotherapy was 79.7% (1506/1890; meta-analysis: 78%, 95% CI: 74-83%). Across 24 reporting studies, modern preferred chemotherapy (EMA/CO or EMA/EP) was associated with lower mortality (overall: 8.8 versus 9.5%; comparative meta-analysis: 8.1 versus 12.4%, OR 0.42, 95% CI: 0.20-0.90%, 14 studies) and higher likelihood of complete response (overall: 76.6 versus 72.8%; comparative meta-analysis: 75.9 versus 60.7%, OR 2.98, 95% CI: 1.06-8.35%, 14 studies), though studies focused on non-preferred regimens reported comparable outcomes. Mortality was increased for ultra-high-risk disease (30 versus 7.5% high-risk; meta-analysis OR 7.44, 95% CI: 4.29-12.9%) and disease following term delivery (20.8 versus 7.3% following molar pregnancy; meta-analysis OR 2.64, 95% CI: 1.10-6.31%). Relapse rate estimates ranged from 3 to 6%. Conclusions: High-risk GTN is responsive to several chemotherapy regimens, with EMA/CO or EMA/EP associated with improved outcomes. Mortality is increased in patients with ultra-high-risk, relapsed and post-term pregnancy disease.