Purpose The treatment mode in acute vertebrobasilar occlusion (VBO) remains uncertain. We analyzed efficacy and safety of intravenous glycoprotein IIb/IIIa inhibitor (IV GPI) plus subsequent intra-arterial thrombolysis with or without additional endovascular mechanical therapy (percutaneous transluminal angioplasty/stenting or thrombus aspiration) and sought treatment factors that predict good clinical outcome. Methods We retrospectively analyzed 120 cases of patients with angiographically proven acute VBO. Multivariate logistic regression was used to identify independent predictors for clinical outcome and included level of consciousness, age, sex, time to angiography, GPI agent, admission mode, occlusion type, recanalization success, and endovascular treatment mode. Clinical follow-up was dichotomized in no to moderate disability (modified Rankin scale (mRS) 0–3) vs. severe disability or death (mRS 4–6). Results Median National Institutes of Health stroke scale (NIHSS) score on admission was 32, and mean NIHSS score was 24. A total of 49 patients (41 %) developed no to moderate disability (mRS 0–3), and 39 patients (33 %) died. Thrombolysis in myocardial infarction 2/3 recanalization success was achieved in 97 patients (80.8 %). Symptomatic intracerebral hemorrhages occurred in 11 patients (9 %). Mild impairment of consciousness (p < 0.001) and embolic occlusion type (p = 0.01) were significant predictors of favorable outcome. Clinical outcome in recanalized patients was better, but not statistically significant (p = 0.055). Conclusions Our results indicate that combined therapy with IV GPI and subsequent endovascular therapy may be a valid treatment strategy in acute VBO. With this treatment approach, a preserved vigilance before treatment and an embolic occlusion type are associated with no to moderate disability.