Background: The recently proposed Staging of Airflow Obstruction by Ratio (STAR) system classifies severity based on the FEV₁/FVC ratio, potentially offering improved prognostic performance. This study aimed to evaluate the prognostic performance of STAR in patients hospitalized for COPD exacerbation. Methods: A retrospective observational single-center study was conducted including COPD patients who were discharged after hospitalization for a severe exacerbation at a university hospital. The clinical and spirometric data in a stable condition, GOLD classification, STAR system, and mortality outcomes were recorded. Results: A total of 197 patients (23% female) were included. The follow-up was performed for a minimum of 38 months or until death if it occurred earlier. During the study period, 91 patients died (46%). Patients were distributed according to the STAR classification as follows: 21% in STAR 1, 32% in STAR 2, 28% in STAR 3, and 19% in STAR 4. The agreement between STAR and GOLD was fair (Cohen’s kappa = 0.28), with a moderate correlation (Tau-b = 0.49, p < 0.001). STAR grades 2 to 4 demonstrated progressively increasing mortality, while STAR grade 1 showed a mortality similar to grade 2. STAR showed a trend toward a superior discrimination for mortality than GOLD (AUC 0.63 [95%CI 0.55–0.71] vs. 0.55 [0.47–0.63]; p = 0.055), although BODEx remained the most accurate predictor (AUC = 0.70 [0.63–0.77]). Conclusions: The STAR system effectively stratified the mortality risk among hospitalized COPD patients across grades 2 to 4. However, STAR grade 1 failed to differentiate patients with a lower risk. Although STAR may underestimate severity in individual patients with relatively preserved ratios, its integration into clinical evaluation could enhance prognostic assessments.