OBJECTIVE: The objective of the present research was to examine the correlation between the neutrophil-to-lymphocyte ratio (NLR) and stroke progression (SP) as well as the functional outcome following an ischemic stroke (IS). METHODS: The current study was conducted as prospective observational research. A cohort of 341 participants diagnosed with IS was included in the study from March 2019 to August 2021. This study's primary measure of interest was the occurrence of SP within the initial week following hospital admission. The secondary outcome was functional status 3 months after IS as measured by a modified Rankin scale score. The association between NLR with SP, and poor functional outcomes was examined using multivariate logistic regression. The predictive value of NLR for SP and poor functional outcomes was evaluated using the receiver operating characteristic (ROC) curve. RESULTS: Among the 341 enrolled patients, 56 (16.4%) had SP, and 285 (83.6%) had no SP. The results of the multivariate logistic regression analysis demonstrated that the existence of diabetes mellitus and the NLR were independently associated with SP and poor functional outcomes. The area under the ROC curve of NLR in predicting poor functional outcome was 0.6117 (95% confidence interval, .5341-.6893, p = .0032), and the optimal cut-off point was 4.2139. The sensitivity and specificity of NLR in predicting poor functional outcomes were 52.7% and 72.0%, respectively. CONCLUSION: Patients with acute IS exhibited a very high incidence of SP. NLR may be a valuable prognostic indicator in clinical practice because it was independently associated with SP and a poor functional outcome.