Introduction Cancer patients receiving myelosuppressive chemotherapy are vulnerable to febrile neutropenia (FN) which contributes to poor treatment outcomes. The use of granulocyte colony-stimulating factors is administered to prevent chemotherapy-induced neutropenia. The introduction of biosimilars has allowed for greater cost-savings while maintaining safety and efficacy. This retrospective study assessed the incidence of FN and related treatment outcomes and the cost minimization of a pegfilgrastim biosimilar and its reference. Methods A retrospective chart review of breast cancer patients receiving (neo) adjuvant chemotherapy from February 2017 to May 2020 was conducted. The endpoints included the incidence of FN, the occurrence of dose reduction (DR), dose delay (DD) and pain. A cost minimization analysis was performed from a third-party payer perspective. Results One hundred Neulasta® and 74 Lapelga® patients were included in the first-cycle analysis. The rate of FN in cycle 1 for Neulasta® and Lapelga® was 2/100 and 4/74, respectively; risk difference (RD) = 3.4%; 95% CI: –2.4 to 9.2%. Eighty-three Neulasta® and 59 Lapelga® patients were included in the all-cycle analyses, where DR was reported in 76 (15%) Neulasta® cycles vs 33 (10%) Lapelga® cycles (RD = –3.6, 95% CI: –10.2 to 2.9). DD was reported in 20 (4%) Neulasta® cycles vs. 11 (3.5%) Lapelga® cycles (RD = –0.3; 95% CI: –2.7 to 2.0). Adverse events were similar between groups. Cost minimization using a cohort of 20,000 patients translated into an incremental savings of $21,606,800 CAD for each cycle. Conclusion The biosimilar pegfilgrastim was non-inferior to the reference biologic based on FN incidence in addition to related outcomes including DR and DD.