The poor thermal and acid stabilities of anthocyanins greatly limit their industrial applications as functional food ingredients. This work investigated the ability of the Maillard reaction products (MRPs) of whey protein isolates and glucose to enhance the thermal stability of anthocyanins over the pH range of 2.0–7.0. Anthocyanin dispersions were subjected to up to 120 min of thermal treatment at 80 °C. The improvement in the color stability and antioxidant capacity of the anthocyanin dispersions indicated that MRP remarkably inhibited anthocyanin degradation. Fluorescence spectroscopy results suggested that anthocyanins and MRPs form complexes through hydrophobic interactions. These complexes effectively attenuated anthocyanin degradation under heat treatment at pH 6.0. The particle sizes of MRPs alone or in complex with anthocyanins remained unchanged after heating. The novel protein delivery system proposed in this study expands the applications of anthocyanins as acid- and heat-stable functional food ingredients.