Despite ongoing advancements in the field of medicine, glioblastoma multiforme (GBM) is presently incurable, making this advanced brain tumor the deadliest tumor type in the central nervous system. The primary treatment strategies for GBM (i.e. surgical resection, radiation therapy, chemotherapy, and newly incorporated targeted therapies) fail to overcome the challenging characteristics of highly aggressive GBM tumors and are presently given with the goal of increasing the quality of life for patients. With the aim of creating effective treatment solutions, research has shifted toward utilizing injectable biomaterial adjuncts to minimize invasiveness of treatment, provide spatiotemporal control of therapeutic delivery, and engage with cells through material-cell interfaces. This review aims to summarize the limitations of the current standard of care for GBM, discuss how these limitations can be addressed by local employment of injectable biomaterial systems, and highlight developments in the field of biomaterials for these applications.