Biodegradable implants such as zinc-based (Zn) alloys have emerged as promising substitutes for conventional implant materials as they can eliminate secondary surgeries and reduce long term complications that are associated with traditional implants. Based on literature studies, addition of manganese (Mn) into Zn-based has shown to strengthen the Zn matrix, while carbon nanofibers (CNF) demonstrate excellent biocompatibility as reinforcement materials. However, the mechanical performance of these composites during the fabrication can be significantly influenced by processing parameters, which limit their reliability for implant applications. Compaction time during fabrication of brittle zinc composites can critically influence the density and mechanical properties of the samples in powder metallurgy (PM). To address this limitation, Zn-0.8Mn composites reinforced with 0.1% CNF were fabricated using powder metallurgy (PM) procedure with compaction times varied at 1, 3, 5, 7 and 9 min. This parametric study investigates the influence of compaction time on the mechanical performance and microstructural features of Zn–0.8Mn/0.1CNF composites. Compressive strength has been measured through uniaxial compression testing, while scanning electron microscopy (SEM) was used to study fracture features and changes in porosity across the different compaction times. From the results, 3 min compaction times demonstrated highest compressive strength of 149.40 MPa with 60.62 µm pores size, while excessive compaction caused hardening of the samples. In conclusion, this study found that compaction time maximizes densification and strength, providing practical guidance for optimizing Zn–Mn/CNF composites for orthopaedic applications.