Purpose: Tislelizumab is an anti-programmed cell death protein 1 (anti-PD-1) monoclonal antibody specifically designed to minimize binding to Fry receptors (Fc gamma R). Patients and Methods: Here, we present the extended 3-year follow-up of a phase II study of tislelizumab in 70 patients with relapsed/refractory classical Hodgkin lymphoma (cHL) who failed or were ineligible for autologous stem cell transplantation. Results: With a median follow-up of 33.8 months, the overall response rate by the independent review committee was 87.1%, and the complete response (CR) rate was 67.1%. Responses were durable as shown by a median duration of response of 31.3 months, and median progression-free survival (PPS) of 31.5 months. The 3-year PFS and overall survival rates were 40.8% and 84.8%, respectively. Treatment-related adverse events (TRAEs) of any grade occurred in 97.1% of patients; the grade >= 3 TRAE rate was low (31.4%), and only 8.6% of patients experienced adverse events leading to treatment discontinuation. Correlative biomarker analysis showed that Fc gamma RI-expressing macrophages had no observed impact on either the CR rate or PFS achieved with tislelizumab, which may be potentially related to its engineered Fc region. Conclusions: With extended follow-up, tislelizumab yielded long-term benefits and demonstrated a favorable safety profile for patients with relapsed/refractory cHL.