Dental caries is a highly prevalent chronic infectious disease worldwide. However, traditional preventive agents, such as antimicrobials and fluorides, face limitations including the induction of bacterial resistance and disruption of oral microecological balance. Emerging as a novel strategy, microecological regulation using probiotics to "combat bacteria with bacteria" offers a promising alternative for caries prevention. Nevertheless, current clinical probiotic products generally suffer from short retention times in the oral cavity, susceptibility to saliva rinsing, and difficulty in achieving effective colonization on dental surfaces. As an innovative delivery system, hydrogels can efficiently encapsulate probiotics, achieve lesion-targeted colonization, and significantly prolong retention time. These hydrogel systems exert anti-caries effects through competitive exclusion of cariogenic bacteria, pH regulation, secretion of antimicrobial substances, and immune modulation. This article reviews recent research progress on probiotic-loaded anti-caries hydrogels, with a particular focus on the anti-caries mechanisms, principles of strain selection, hydrogel design mechanisms, and the regulatory roles of degradation kinetics in probiotic delivery and therapy. Overall, this review aims to provide a theoretical reference for the microecological prevention and clinical translation of dental caries.