Raised intracranial pressure (ICP) is associated with worse outcomes after acute brain injury, and clinical guidelines advocate early treatment of intracranial hypertension. ICP-lowering therapies are usually administered in a stepwise manner, starting with safer first-line interventions, while reserving higher-risk options for patients with intractable intracranial hypertension. Decompressive craniectomy is a surgical procedure in which part of the skull is removed and the underlying dura opened to reduce brain swelling–related raised ICP; it can be performed as a primary or secondary procedure. After traumatic brain injury, secondary decompressive craniectomy is most commonly undertaken as a last-tier intervention in a patient with severe intracranial hypertension refractory to tiered escalation of ICP-lowering therapies. Although decompressive craniectomy has been used in a number of conditions, it has only been evaluated in randomized controlled trials after traumatic brain injury and acute ischemic stroke. After traumatic brain injury, decompressive craniectomy is associated with lower mortality compared to medical management but with higher rates of vegetative state or severe disability. In patients with stroke-related malignant hemispheric infarction, hemicraniectomy significantly decreases mortality and improves functional outcome in adults <60 years of age. Surgery also reduces mortality in those >60 years, but results in a higher proportion of severely disabled survivors compared to medical therapy in this age group. Decisions to recommend decompressive craniectomy must always be made not only in the context of its clinical indications but also after consideration of an individual patient’s preferences and quality of life expectations. This narrative review discusses the management of intractable intracranial hypertension in adults, focusing on the role of decompressive craniectomy in patients with traumatic brain injury and acute ischemic stroke.