Objectives To investigate the efficacy and safety of intravenous thrombolysis (IVT) in patients with acute ischemic stroke (AIS) presenting within 4.5 to 9 hours in a Chinese real-world study, providing evidence for optimizing thrombolytic decision-making in this extended time window. Methods Patients with AIS who underwent IVT at the Third People’s Hospital of Chengdu between June 2023 and July 2025 were retrospectively enrolled. They were categorized into a standard time window group and an extended time window group based on the onset-to-treatment time. The inverse probability of treatment weighting (IPTW) method based on propensity scores was employed to balance baseline characteristics between the two groups. Multivariate logistic regression analysis was used to evaluate functional independence, the incidence of symptomatic intracerebral hemorrhage, and mortality at 3 and 6 months post-discharge. Results A total of 362 patients were enrolled, including 50 in the extended time window group and 312 cases in the standard time window group. After IPTW adjustment, baseline characteristics were well-balanced between the groups (P>0.05). Multivariate logistic regression analysis revealed that IVT in the extended time window was not an independent risk factor for modified Rankin Scale 0-1, the incidence of symptomatic intracerebral hemorrhage, or mortality (P>0.05). Conclusion In real-world clinical practice, for AIS patients strictly selected via multimodal imaging, IVT administered in the extended time window is not inferior to treatment within the standard time window regarding key outcomes such as functional independence and safety.