Decompressive craniectomy (DC) is a life-saving procedure conducted to treat refractory intracranial hypertension. Although DC reduces mortality of severe Acquired Brain Injury (sABI) survivors, it has been associated with severe long-term disability. This observational study compares functional outcomes at discharge from an Intensive Rehabilitative Unit (IRU) between sABI patients with and without DC. sABI patients undergoing DC before entering the Don Gnocchi Foundation IRU were compared with a group of sABI patients who did not undergo DC (No-DC group), after matching it by age, sex, aetiology, time post-onset, and clinical status. Inclusion criteria were: diagnosis of sABI, age 18+, time from the event <90 days. A total of 87 (DC: 47) patients were included (median age: 60.5 IQR = 17.47). The two groups did not differ for admission clinical features except for the tracheostomy presence (more frequent in DC, p < 0.001). No significant differences were also found at discharge. DC group presented a significantly longer length-of-stay than No-DC group (p < 0.001) and a longer time to tracheostomy removal (p = 0.036). DC was not found to influence outcomes as consciousness improvement, tracheostomy removal, oral intake and functional independence. sABI patients with DC improved after rehabilitation as much as No-DC patients did but they required a longer stay. Implications for Rehabilitation Decompressive craniectomy (DC) is practiced during the acute phase after hemorrhagic, ischemic, traumatic severe brain injury as a life-saving procedure to treat refractory intracranial hypertension DC has been associated with follow-up severe long-term disability, but no study yet addressed whether DC may affect intensive rehabilitation outcomes. Undergoing a DC is not a negative prognostic factor for achieving rehabilitation goals after a severe acquired brain injury DC must be taken into account when customizing rehabilitation pathway especially because these patients required a longer time to reach the outcomes.