Humans experience a unified self that integrates our mental lives and physical bodies, but many studies focus on isolated domains of self-knowledge. We tested the hypothesis that knowledge of one's mind and body are related by examining metamemory and interoception. We evaluated two dimensions of metamemory and interoception: subjective beliefs and the accuracy of those beliefs compared to objective criteria. We first demonstrated, in two studies, that metamemory beliefs were positively correlated with interoceptive beliefs, and this was not due to domain-general confidence. Finally, we showed that individuals with better metamemory accuracy also had better interoceptive accuracy. Taken together, these findings suggest a common mechanism subserving knowledge of our cognitive and bodily states.