Abstract Background Nivestym, a biosimilar granulocyte colony‐stimulating factor (G‐CSF) to the originator filgrastim (Neupogen), is now being used for the mobilization of peripheral blood stem cells (PBSC) in allogeneic hematopoietic stem cell transplantation (allo‐HSCT). We aim to compare the efficacy of Nivestym and Neupogen for PBSC mobilization in healthy allogeneic donors. Methods We conducted a retrospective single‐center study including 541 adult allo‐HSCT donors receiving Nivestym (January 2013–July 2020), or Neupogen (July 2020–June 2023) for donor PBSC mobilization. Bivariate analysis was conducted using SPSS version 28. Statistical significance was determined at a p ‐value <.05. Results Our study included 541 allo‐HSCT donors who received Neupogen ( n = 345, 64%) or Nivestym ( n = 196, 36%) for PBSC mobilization. The median age was 47 years (range 17–76). The median donor weight was 86 kg (95% confidence interval CI: 87–91). Donors receiving Neupogen had similar pre‐G‐CSF white blood cell count, CD34 + percentages, and circulating CD34 + count compared with donors receiving Nivestym. The Neupogen group had similar median PBSC product total neutrophil count, CD34 + percentage, absolute CD34 + count, and infused CD34 + dose compared with the Nivestym group. For donors aged 35 years or younger, the median CD34 + dose was higher in donors who received Neupogen compared with Nivestym (6.9 vs. 6.3 million cells/kg, p = .044). Conclusions Nivestym demonstrated similar efficacy for PBSC mobilization compared with Neupogen among allo‐HSCT donors. In donors aged 35 years or younger, a slightly lower PBSC product CD34 + count was noted with Nivestym compared with Neupogen.