Bees are essential pollinators for most crops and play an invaluable role in sustaining our planet's ecosystems. In the past decades, dramatic reductions of bee colonies caused significant economic losses all through the world. Recently, it was found that social bees (genus Apis and Bombus) harbor simple and highly specific gut microbiota. Thus, there is tremendous interest in understanding the role of the gut symbionts in shaping physiology, behavior, and fitness traits of the host. Moreover, the social bee microbiota shows similarity to those of human and other animals, such as the transmission through social interactions. This review focuses on the most recent studies on the function of the bee gut microbiota in food digestion, nutrition provision, and defense against pathogens. We finally propose the opportunity of bee gut as a new model system for research on human nutrition and health.