In this study, biodegradable bamboo fiber/PLA composites (BPCs) modified using bamboo charcoal (BC)/ZnO were prepared. The effects of BC/ZnO addition on the mechanical properties and antibacterial properties of BPCs were investigated. The chemical structure, microscopic morphology, and crystallization of the composites were analyzed using FTIR, SEM, and XRD, respectively. The results showed that in terms of mechanical strength, when the addition of BC was 2%, the tensile impact and flexural strength of the BPCs were most obviously improved, with a tensile strength of 51.6 MPa. However, when the addition of BC was more than 2%, the uneven dispersion of too much BC in the BPCs resulted in a reduction in their mechanical strength. A certain amount of ZnO did not affect the crystallinity of the BPCs. In addition, the uneven distribution of ZnO and its poor compatibility with PLA resulted in a deterioration in the tensile properties of the BPCs. In terms of antibacterial properties, when 2% ZnO was added, the BPCs had better antibacterial properties against Escherichia coli and Staphylococcus aureus, with values of 58.9% and 52.5% against both, respectively. BPC biodegradable materials with both mechanical strength and antimicrobial properties have promising medical uses.