Fifty percent of patients who undergo endovascular thrombectomy (EVT) for large-vessel occlusion exhibit unfavorable outcomes. The primary factor is attributed to persistent brain impairment even after successful EVT. The prominent vessel sign (PVS) on magnetic resonance susceptibility-weighted imaging reflects the territory of dysmetabolism and may facilitate an expeditious assessment for prognostication. We aimed to examine the relationship between PVS after EVT and the occurrence of early neurological deterioration (END) and 3-month outcomes. Patients who underwent EVT and multimodal magnetic resonance imaging were included. END was defined as an increase of ≥2 in the National Institutes of Health Stroke Scale within 72 hours after EVT. Symptomatic intracranial hemorrhage, malignant edema, and surgical complications were defined as definite END, whereas the other symptoms were categorized as unexplained END (ux-END). The PVS-Alberta Stroke Program Early CT Score (ASPECTS) score was used to evaluate the asymmetric cerebral venous signal on the susceptibility-weighted imaging sequences semiquantitatively. A total of 116 eligible patients were included, 18 (15.5%) of whom presented with ux-END. The 72hour National Institutes of Health Stroke Scale was strongly correlated with diffusion-weighted imaging infarct volume and PVS-ASPECTS and was significantly higher in the ux-END group (16 ± 6 vs. 5 ± 4, P= 0.001). The PVS-ASPECTS score was significantly associated with poor outcomes (odds ratio 2.551, 95% confidence interval (CI) 1.722-3.780, P<0.001), and PVS-ASPECTS (area under the curve 0.884, 95% CI 0.815-0.953, P<0.001) was superior to diffusion-weighted imaging infarct volume (area under the cure 0.720, 95% CI 0.620-0.820, P= 0.001) in predicting 3-month poor outcome. At the optimal cut-off of 2, the PVS-ASPECT predicted poor outcomes with a sensitivity of 89.7% and a specificity of 78.2%. PVS 72 hours after EVT correlated with ux-END. The PVS-ASPECTS is a more reliable predictor of stroke prognosis and provides valuable information regarding post-EVT management.