The management of tandem extracranial internal carotid artery and intracranial large vessel occlusion during endovascular thrombectomy (EVT) for acute ischemic stroke (AIS) has been under-investigated. We sought to investigate outcomes of AIS patients with tandem occlusion (TO) treated with carotid artery stenting (CAS) compared to those not treated with CAS (no-CAS) during EVT. We performed a cohort study using data from AIS patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke. Outcomes were 3months' mortality, functional outcome, complete and successful recanalization, any intracranial hemorrhage, parenchymal hematoma and symptomatic intracerebral hemorrhage. Among 466 AIS patients with TO, CAS patients were 122 and no-CAS patients were 226 (118 excluded). After adjustment for unbalanced variables, CAS was associated with a lower rate of 3months' mortality (OR 0.407, 95% CI 0.171-0.969, p = 0.042). After adjustment for pre-defined variables, CAS was associated with a lower rate of 3months' mortality (aOR 0.430, 95% CI 0.187-0.989, p = 0.047) and a higher rate of complete recanalization (aOR 1.986, 95% CI 1.121-3.518, p = 0.019), successful recanalization (aOR 2.433, 95% CI 1.263-4.686, p = 0.008) and parenchymal hematoma (aOR 2.876, 95% CI 1.173-7.050, p = 0.021). CAS was associated with lower 3months mortality (OR 0.373, 95% CI 0.141-0.982, p = 0.046) and higher rates of successful recanalization (OR 2.082, 95% CI 1.099-3.942, p = 0.024) after adjustment for variables associated with 3months' mortality and successful recanalization, respectively. Among AIS patients with TO, CAS during EVT was associated with a higher rate of successful reperfusion and a lower rate of 3months' mortality.