Abstract BACKGROUND Cerasus humilis is an edible medicinal plant, rich in minerals, organic acids, proteins, and carbohydrates, with particularly high organic acid content. Its fruit contains high levels of antioxidants such as vitamins, amino acids, flavonoids, proanthocyanidins, and anthocyanins, which provide strong free‐radical scavenging activity and support its use in antioxidant‐rich foods and for nutritional health. This study examined changes in organic acids, antioxidant compounds, antioxidant enzyme activity, and antioxidant capacity during fruit development. RESULTS During development and maturation, the composition of organic acids and antioxidant‐related indices in C. humilis fruit changed. Malic acid reached 15.61 g kg −1 FW at full ripeness, accounting for 95.01% of total organic acids. Correlation analysis indicated that organic acids, antioxidant compounds, and antioxidant enzymes were closely linked, collectively determining antioxidant capacity. Different acids had distinct effects: malic acid influenced the scavenging rate, whereas citric and oxalic acids increased both the antioxidant compounds and enzymes that contribute to primary antioxidant capacity. CONCLUSION The antioxidant capacity of C. humilis fruit is highest during early development and decreases in later stages, providing a theoretical basis for the development of antioxidant‐rich products and determining optimal harvest time. © 2025 Society of Chemical Industry.