Consumption of foods with high total antioxidant capacity (TAC) can reduce the risk of several illnesses in humans caused by the overproduction of pro-inflammatory cytokines in the body. Therefore, it is awfully important to build a rapid and sensitive platform for detecting TAC. In this work, a one-pot synthesized Bi_0.3Fe_1.7MoO₆ with intrinsic peroxidase-like activity was made up for the shortcomings of natural enzymes for TAC detection. The peroxidase-like activity was evaluated by TMB chromogenic system in the presence of H₂O₂. Bi_0.3Fe_1.7MoO₆ showed a higher affinity for H₂O₂ and TMB than that of natural horseradish peroxidase (HRP) and can be used to establish ascorbic acid (AA) sensing platform, which achieved a low detection limit (0.77 nM) and a good linear range (8–64 μM). The method has been proved to be applicable for the selective, stable, and reproducible TAC determination of food samples. Furthermore, the established TAC detection method applied to actual samples endows great potential for nutrition assessment.