In response to the industrial challenge of unstable quality in blended coconut-based beverages such as pandan coconut beverages, this study focused on pandan coconut beverages prepared from fresh coconut flesh and pandan leaves. Based on formulation optimization, the effects of different sterilization processes on product quality were further compared, with a comprehensive evaluation of system stability, antioxidant capacity, sensory quality, and flavor characteristics. Response surface methodology was used to determine the relatively optimal formulation, consisting of 7.25% coconut flesh, 0.50% pandan puree, 0.40% casein, and 6.70% white sugar. The pasteurized sample exhibited a TSI of 0.60, an average particle size of 0.18 μm, and an absolute zeta potential of 17.13 mV. The DPPH and O2?? radical scavenging rates were 43.55% and 39.80%, respectively. The pasteurized and Ultra-high temperature instantaneous sterilization (UHT)-treated samples showed relatively high sensory scores of 88.40 and 87.20, respectively. Electronic nose and principal component analysis (PCA) results indicated differences in the overall odor-response profiles between the unsterilized beverage and the three sterilized samples. The UHT-treated sample showed a greater deviation from the samples subjected to the other two sterilization treatments and exhibited higher sensor response values. The results demonstrated that different sterilization processes produced distinct effects on the stability and electronic-nose flavor profiles of pandan coconut beverage. Among them, the pasteurized sample exhibited the best 24 h stability and relatively superior antioxidant capacity, whereas the UHT-treated sample showed higher electronic-nose sensor responses and a more distinct odor profile than the samples treated by the other two sterilization methods. These findings provide theoretical support for the precise optimization of sterilization processes in pandan coconut beverage production.