Glioblastoma (GBM) remains a significant cause of cancer-related mortality in pediatric and adult patients with limited treatment options. Immunotherapy represents a promising new therapeutic approach in many solid and hematologic malignancies, including GBM, although only a subset of patients responds clinically. Thus, current efforts are focused on identifying patients most likely to benefit from immune-based therapies. The cancer immunogenomics approach identifies candidate neoantigens from genomics information and represents a potentially exciting new space in precision neuro-oncology. In this review, we discuss the role of neoantigens in GBM both as predictive biomarkers and as targets of immunotherapy.