During the lactic acid tenderization process of yak meat, an observable phenomenon is the color browning. To delve into the underlying causes and devise solutions, this study meticulously injected varying concentrations and volumes of lactic acid into yak meat samples, the freshness and color appearance of the meat were assessed by measuring metmyoglobin (MetMb) content, color parameters, lipid oxidation levels, and conducting sensory evaluations. Furthermore, the mechanisms behind the color alterations were elucidated by quantifying the activity of MetMb reductase and lactate dehydrogenase (LDH). The results indicated that when lactic acid was introduced at a concentration of 0.4 mol/L, accompanied by an injection volume equivalent to 2.5% of the meat weight, yak meat underwent a marked browning. This transformation was primarily attributed to the diminished MetMb reductase activity. Under specific pH conditions, augmented mitochondrial respiration fosters the formation of MetMb, culminating in its substantial accumulation and subsequently altering the color of the yak meat. Conclusively, this research underscores that the combined factor of injecting lactic acid at a concentration of 0.4 mol/L and a volume corresponding to 2.5% of the meat weight serves as a crucial catalyst for the browning of yak meat, emphasizing the need for careful regulation of these parameters during the tenderization process.