Glioblastomas (GBM), one of the most common tumors of the central nervous system, are associated with poor prognosis, even with all the scientific development of the last decades. Individual survival, however, is not homogenous among GBM patients, and multiple factors are related to their outcome, including age, biological characteristics of the tumor, and extent of treatment. Extent of resection (EOR) plays a major role as an independent modifiable factor associated with improved overall and progression-free survival. Achievement of maximal safe resection, removing as much as possible the tumor while preserving the neurological function, is the main goal of the current surgical treatment of GBM. To reach this objective, different technologies and surgical techniques have been introduced in neuro-oncology surgery, including functional neuronavigation systems, ultrasound surgery, intraoperative MRI scan, and intraoperative cortical and subcortical mapping techniques. In the current manuscript, we examine the impact of EOR on the prognosis of GBM patients and the benefits and limitations of modern adjuvant techniques used for resection of these lesions.