Thermal food processing, which causes the alteration and decomposition of natural pigments, especially anthocyanins, often leads to its lower stability. This study aimed to determine the effect of ascorbic acid and citric acid and the combination of these two chemicals on the thermal stability of the anthocyanin in the raspberry-pomegranate-banana nectar during heating at different temperatures (85°C, 90°C, and 95°C) and also investigated the influence of storage conditions (8°C ± 2°C and 28°C ± 2°C) on the stability of anthocyanin in the product. Anthocyanin degradation during heating as well as storage was followed by a first-order kinetic model with a high coefficient of determination (R2 > 0.94) and low root-mean-square error (RMSE < 0.015). By combining ascorbic acid and citric acid used in the nectar, anthocyanin showed more stability during pasteurization. It was found that the highest anthocyanin stability during storage was obtained at 8°C ± 2°C and the half-life was 11.76 weeks.