BACKGROUND: Early neurological deterioration after endovascular thrombectomy (EVT) is associated with poor prognosis. National Institutes of Health Stroke Scale (NIHSS) score measured at 24 h after EVT may be a better outcome predictor than other methods that focus on changes in NIHSS. Nevertheless, clinical fluctuations in ischemic stroke patients during the immediate phase after symptoms onset are well recognized. Therefore, a delayed NIHSS evaluation may improve prognostic accuracy. We evaluate the 7-day NIHSS in predicting long-term patient outcomes after EVT. METHODS: This was a multi-center retrospective cohort study of 300 consecutive ischemic stroke patients with large vessel occlusion who underwent EVT at three-stroke centers in China from August 2018 to March 2022. NIHSS was recorded on admission, pre-EVT, 24 h, and 7 days after EVT. RESULTS: A total of 236 eligible patients were subdivided into two groups: 7-day NIHSS ≤6 and NIHSS >6 post-EVT. 88.29% achieved a favorable outcome (modified Rankin Scale 0-2) in the NIHSS ≤6 group compared to 15.20% in the NIHSS >6 group at 90 days, and an improved favorable outcome in the former group was observed after adjusting for potential confounding factors (adjusted odds ratio 39.7, 95% confidence interval, 17.5-89.7, p < 0.001). CONCLUSION: The 7-day NIHSS score may be a reliable predictor of 90-day stroke patient outcome after EVT.