Lithium-ion batteries (LIBs) have dominated the energy storage field due to their high energy density, long cycle life, and environmental friendliness. In this study, we systematically investigated the electrochemical properties of phosphorus (P)-doped γ-graphyne as a promising LIBs anode material using density functional theory calculations. The formation energy and cohesive energy of γ-graphyne at varying doping concentrations are calculated, demonstrating excellent experimental synthesizability of P-doped γ-graphyne. Notably, the P-doped system exhibits enhanced electrical conductivity compared to pristine γ-graphyne. The adsorption energy of a single lithium (Li) atom on P-doped γ-graphyne is determined to be -3.72 eV, significantly higher than those of N-doped, Si-doped, and intrinsic γ-graphyne. Even with increasing Li storage, the Li adsorption energy remains greater than the cohesive energy of bulk lithium, while the average open-circuit voltage falls within the optimal range of 0-1 V, ensuring high operational safety. Remarkably, the theoretical Li storage capacity of P-doped γ-graphyne reaches 1150.68 mAh/g, which is 1.85 times that of pristine γ-graphyne and 3.09 times that of conventional graphite. Furthermore, the diffusion barrier calculations reveal that P-doped γ-graphyne substantially reduces the Li-ion migration energy barrier, indicating favorable lithium diffusion kinetics. In summary, P-doped γ-graphyne demonstrates exceptional advantages in specific capacity, structural stability, electrical conductivity, and Li-ion diffusion kinetics, providing critical theoretical insights and experimental guidance for designing next-generation high-performance LIBs anode materials.