We report survival outcomes for patients with advanced-stage hepatocellular carcinoma (HCC) with portal vein thrombosis (PVT) treated with ⁹⁰Y radioembolization. Methods: With institutional review board approval, we searched our prospectively acquired database for ⁹⁰Y patients treated between 2003 and 2017. Inclusion criteria were patients who had HCC with tumor PVT. Patients with metastases were excluded. Laboratory data were collected at baseline and 1 mo after ⁹⁰Y radioembolization. Toxicity grades were reported according to the Common Terminology Criteria for Adverse Events, version 4.0, and long-term survival outcomes were reported and stratified by Child-Pugh class (CP). Overall survival was calculated using the Kaplan-Meier method. Multivariate analysis was performed using Cox proportional hazards regression. A subanalysis for patients with a high level of α-fetoprotein (AFP) (>100 ng/dL) was conducted. Results: In total, 185 patients with HCC PVT underwent ⁹⁰Y radioembolization. Seventy-four (40%) were CP-A, 51 (28%) were CP-B7, and 60 (32%) were ≥CP-B8. New albumin, bilirubin, and alkaline phosphatase grade 3/4 toxicities were, respectively, 3%, 10%, and 0% for CP-A; 14%, 12%, and 6% for CP-B7; and 23%, 32%, and 3% for ≥CP-B8. Median overall survival for CP-A patients was 13.3 mo (95% confidence interval [CI], 8.7-15.7 mo). CP-B7 and ≥CP-B8 patients exhibited median overall survival of 6.9 mo (95% CI, 5.3-10.1 mo) and 3.9 mo (95% CI, 2.9-5.0 mo), respectively. Significant overall survival prognosticators on univariate analysis were albumin, bilirubin, ascites, tumor size 5 cm or smaller, focality, distribution, infiltration, Eastern Cooperative Oncology Group status, AFP level, and PVT extent. Multivariate analysis showed the prognosticators of overall survival to be bilirubin, no ascites, tumor size 5 cm or smaller, solitary lesion, baseline AFP level lower than 100 ng/dL, and Eastern Cooperative Oncology Group status. Of 123 patients with a high AFP level (>100 ng/dL), 12 patients achieved restored normal AFP levels (<13 ng/dL) and exhibited median overall survival of 23.9 mo (95% CI, 20.1-124.1 mo). AFP responders at 1 mo had better overall survival than nonresponders, at 8.5 mo versus 4.8 mo (P = 0.018); AFP responders at 3 mo had overall survival of 13.3 mo, versus 6.9 mo for nonresponders (P = 0.021). Conclusion:⁹⁰Y radioembolization can serve as a safe and effective treatment for advanced-stage HCC patients with tumor PVT. Overall survival outcomes are affected by baseline liver function, tumor size, and AFP level.