Over the past several years, the therapeutic landscape for patients with advanced, unresectable, or metastatic hepatocellular carcinoma has been transformed by the incorporation of checkpoint inhibitor immunotherapy into the treatment paradigm. Frontline systemic treatment options have expanded beyond anti-angiogenic tyrosine kinase inhibitors, such as sorafenib, to a combination of immunotherapy approaches, including atezolizumab plus bevacizumab and durvalumab plus tremelimumab, both of which have demonstrated superior response and survival to sorafenib. Additionally, combination treatments with checkpoint inhibitors and tyrosine kinase inhibitors have been investigated with variable success. In this review, we discuss these advances in systemic treatment with immunotherapy, with a focus on understanding both the underlying biology and mechanism of these strategies and their efficacy outcomes in clinical trials. We also review challenges in identifying predictive biomarkers of treatments and discuss future directions with novel immunotherapy targets.