<b><i>Background:</i></b> Basilar artery occlusion (BAO) is a rare stroke subtype with high mortality rates. Best BAO reperfusion strategy is still controversial. <b><i>Objective:</i></b> We aim to describe outcomes of BAO patients submitted to mechanical thrombectomy (MT) in a comprehensive stroke center in Brazil and analyze which previous published computed tomography angiography (CTA) collateral score better predict functional outcomes. <b><i>Methods:</i></b> Retrospective analysis of consecutive BAO patients. CTA was used to evaluate the posterior circulation collateral score (PC-CS), the <i>basilar artery on CTA</i> score, and for the presence of posterior communicating arteries. A favorable outcome was defined as modified Rankin Score ≤3 at 90-days. After univariate analyses, multivariate logistic regression was used to identify if any collateral score independently predicts favorable outcomes. <b><i>Results:</i></b> Between January 2011 and April 2017, 27 (85% male) BAO patients with median NIHSS 26 (IQR 15–32) were identified. Twenty-five (93%) patients were treated with MT devices, and only 2 (7%) patients were treated with angioplasty and stenting. Successful recanalization rate was 85%, and only 1 (3.7%) patient had symptomatic hemorrhagic transformation. Favorable outcomes were reached in 10 (37%) patients. In univariate analysis, female sex, NIHSS, Glasgow coma scale, mild-to-moderate symptoms on admission, onset-to-groin time, and PC-CS predicted favorable outcomes. In multivariate analysis, PC-CS (OR 1.69; 95% CI 1.10–2.60; <i>p</i> = 0.016) and NIHSS (OR 0.84; 95% CI 0.77–0.93; <i>p</i> = 0.001) remained the only independent predictors of favorable outcomes. The PC-CS AUC was 0.80 (95% CI 0.62–0.98; <i>p</i> = 0.012). <b><i>Conclusions:</i></b> MT is a promising strategy for BAO treatment. Among collateral scores, PC-CS was the only independent predictor of favorable outcomes in the present study.