Carbon fiber–reinforced Zn-based composites offer promising wear and corrosion resistance, yet their mechanical performance is limited by weak Zn/C interfacial bonding. Density functional theory (DFT) calculations were employed to systematically investigate the bonding characteristics of Zn/C interfaces and the effects of Zr, Sc, and Y doping on interfacial strengthening. The pristine interface exhibits poor adhesion ( W ad = 1.79 J/m 2), dominated by van der Waals interactions. Transition-metal doping markedly enhances adhesion and reduces interfacial energy ( W ad = 6.50, 6.17, and 6.14 J/m 2; interfacial energy, γ = 2.39, 2.58, and 2.65 J/m 2 for Zr, Sc, and Y) via distinct mechanisms. Zr promotes metallic bonding via d-orbital hybridization with Zn-4p states, Sc forms covalent bonds through 3d–3p orbital overlap with carbon, and Y provides moderate strengthening through delocalized electron redistribution. Tensile separation simulations reveal corresponding increases in separation energy (1.27, 1.02, and 0.91 J/m 2 for Zr, Sc, and Y, respectively). Zr doping exhibits concentration dependence, with optimal performance at 5/9–7/9 monolayer ( W ad ≫ 7.94 J/m 2, γ = 1.14–1.38 J/m 2, and tensile strength > 17.39 GPa). These results clarify the electronic origins of transition-metal-induced Zn/C interfacial strengthening and provide theoretical guidance for designing high-performance Zn-based carbon fiber composites.