Multimodal strategies combining transarterial therapy, radiotherapy, and immune checkpoint inhibition show therapeutic promise in advanced or unresectable hepatocellular carcinoma (HCC), though systematic evidence remains limited. We evaluated the clinical efficacy, safety, and immune-modulating effects of this triple combination. Databases (PubMed, Embase, Cochrane Library, Web of Science) were searched, and clinical outcomes were pooled using random-effects models. Thirteen studies (517 patients) met the inclusion criteria. The pooled objective response rate was 53% (95% CI, 43–63%), disease control rate was 77% (95% CI, 68–84%), and summary median overall survival was 20.2 months (95% CI, 18.6–21.9 months; 7 studies). Median progression-free survival ranged from 5.6 to 35.5 months. Grade ≥3 treatment-related adverse events occurred in 14% of patients (95% CI, 1–74%). Subgroup analyses demonstrated consistent response rates across varying treatment architectures and radiation modalities. Available translational data showed dynamic changes in circulating biomarkers, immune subsets, and intratumoral inflammation. In conclusion, combining transarterial therapy, radiotherapy, and immunotherapy demonstrates encouraging clinical activity with manageable safety and preliminary evidence of immune remodeling in advanced HCC. Prospective randomized trials are warranted.