This study investigates the mechanism of phosphorylation in the regulation of apoptosis-mediated meat tenderization during postmortem aging. The results found that the pork muscle exhibited apoptotic potential at early postmortem (48 h) and showed more tenderness at late postmortem, as evidenced by the increase in mitochondrial membrane permeability (MMP), Ca²⁺ level, reactive oxygen species (ROS) content, and caspases activity at 0 h to 48 h, and decreases in ATP level at 0 h to 24 h and shear force at 12 h to 120 h (p < 0.05). Phosphoproteomic analysis revealed that phosphorylation regulated apoptosis by modulating ATP and calcium bindings as well as apoptotic signaling, which occurred within early 12 h and mainly occurred at 12 h to 48 h postmortem. Moreover, differential expression of phosphoproteins demonstrated that phosphorylation regulated oxidative stress-induced apoptosis and rigor mortis, thereby promoting the development of meat tenderness. Our results provide insights into the roles of phosphorylation in various physiological processes that affect meat tenderness.