Background It is uncertain whether mechanical thrombectomy (MT) increases the probability of a good outcome (modified Rankin Scale (mRS) 0–2) in patients with Alberta Stroke Program Early CT Score (ASPECTS) 0–6. Objective To assess the impact of MT in patients with pretreatment ASPECTS 0–6. Methods According to PRISMA guidelines, we performed a systematic search of three databases for series of patients with ASPECTS 0–6 treated by MT. Random-effects meta-analysis was used to pool the following: rate of mRS 0–2 at 3 months follow-up, symptomatic intracranial hemorrhage (sICH), and mortality rates. Results We included 17 studies and 1378 patients with ASPECTS 0–6 (1194 MT, 184 medical management). The rate of mRS 0–2 was 30.1% and 3.2% after MT and medical management, respectively. MT gave higher odds of mRS 0–2 (OR 4.76, p=0.01). Patients with ASPECTS 6 and 5 had comparable rates of good outcome (37.7% and 33.3%, respectively). Overall, the rate of mRS 0–2 was 17.1% in patients with ASPECTS 0–4: 22.1% and 13.9% of patients with ASPECTS 4 and 0–3 were functionally independent, respectively. Successful recanalization (Thrombolysis in Cerebral Infarction grade 2b–3) gave higher odds of mRS 0–2 than unsuccessful reperfusion (OR 5.2, p=0.001). The MT group tended to have lower odds of sICH compared with the controls (OR 0.48, p=0.06). Patients aged <70 years had higher rates of mRS 0–2 than those aged >70 years (40.3% vs 16.2%). Conclusions Patients with ASPECTS 0–6may benefit from MT. Successful reperfusion increases the probability of 3-month functional independence without increasing the risk of sICH. Patients with ASPECTS 5 and 6 have comparable outcomes. MT can still enable approximately one in four patients with ASPECTS 4 to be independent, whereas only 14% of subjects with ASPECTS 0–3 regain a good functional outcome.