Objective: This study examined the clinical features, functional outcomes, and prognostic indicators of acute ischemic stroke (AIS) patients who had an Alberta Stroke Program Early Computed Tomography Score (ASPECTS) ≤ 5 and who underwent mechanical thrombectomy (MT). Methods: We included consecutive AIS patients with ASPECTS ≤ 5 who had received MT at the same hospital. Demographic, clinical, and radiological data were collected and analyzed. Functional outcome at 90 days after treatment was classified as good or poor based on the modified Rankin Scale (mRS). Results: Of the 152 included patients with ASPECTS ≤ 5 who received MT, 64 (42.11%) experienced poor functional outcomes and 32 (21.1%) experienced good functional outcomes. The independent predictors of poor functional outcomes were the presence of respiratory tract infections (OR 3.72, 95% CI 1.17–11.91), modified thrombolysis in cerebral infarction (OR 0.41, 95% CI 0.2–0.83), symptomatic intracerebral hemorrhage (sICH) (OR 4.96, 95% CI 1.36–18.13), and baseline score on the National Institute of Health Stroke Scale (NIHSS) (OR 1.18, 95% CI 1.03–1.36). Independent predictors of 90-day mortality included time from groin puncture to recanalization (OR 1.03, 95% CI 1.01-1.05), NIHSS scores (OR 1.28, 95% CI 1.12–1.47) and the occurrence of sICH (OR 1.81, 95% CI 1.25-5.75). Conclusion: AIS patients with ASPECTS ≤ 5 can experience good functional outcomes after MT. However, patients with sICH, respiratory infection, higher NIHSS score or failed recanalization are more likely to experience poor functional outcomes. © 2021 Elsevier Inc.