Background: Treating relapsed or refractory classical Hodgkin lymphoma (R/R cHL) remains challenging. This report extends the three-year follow-up period for the phase II YH-S001-04 trial, expanding upon the initial 15.8- month analysis. Methods: Zimberelimab 240 mg was administered every two weeks for two years or until disease progression or death. The endpoint was the objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety. Results: The median follow-up was 38.0 months (3.5-42.8 months). The ORR was 91.6 % (95 % CI, 83.8-95.9). Median PFS was 23.6 months, with a longer PFS in responders (28.5 months) compared to non-responders (9.2 months) (P=0.0098). Complete responders had longer mPFS than partial responders (Not reached vs. 28.5 months, P =0.3469). Relapsed patients had improved mPFS compared to refractory cHL (23.6 vs. 10.6 months, P =0.0061). Patients with <3 lines of therapy showed longer mPFS compared to >= 3 lines (not reached vs. 23.6 months, P =0.0095). The 3-year OS rate was 94.0 % (95 % CI, 85.9-97.4). No serious adverse events with incidence >5 %. Conclusions: With encouraging data on both PFS and OS, zimberelimab demonstrates ongoing efficacy and safety in treating R/R cHL, supporting zimberelimab as an effective treatment alternative for R/R cHL (NCT03655483).