Cutaneous T-cell lymphomas (CTCLs) are rare, usually refractory, and sometimes fatal diseases. Patients presenting with advanced-stage CTCL usually exhibit poor long-term survival outcomes. Only very few treatments have improved progression-free survival (PFS) in advanced CTCL, and no treatment has increased overall survival (OS). In 2023, the results of the CUTALLO trial supported the hypothesis that hematopoietic stem-cell transplantation (HSCT) was associated with significantly longer PFS as compared with standard-of-care treatment among advanced-stage patients although HSCT did not significantly affect OS. We provide herein the final OS data pertaining to the same patient population after a longer median follow-up of 38.9 months. Of the 99 patients included in the analysis, 55 (56%) were assigned to the HSCT group, whereas 44 (44%) were allocated to the non-HSCT group. The updated survival analysis reported that 16 of 55 patients (29%) in the HSCT group and 22 of 44 patients (50%) in the non-HSCT group died. The median OS was not reached in the HSCT group and 51.5 months (95% CI, 26.9 to 51.5) in the non-HSCT group (hazard ratio, 0.40 [95% CI, 0.20 to 0.80]). Compared with the standard of care for advanced CTCL, after extended follow-up, allogeneic HSCT was associated with significantly longer OS.