The mind is embodied, and this is relevant to mental health and psychiatric illness. Interoception is the body-to-brain axis of sensory information flow and its representation at the neural and psychological levels. Interoception is the purported basis for motivation and emotion, and as an inescapable stream of information about the health and functioning of the whole organism, it is proposed to be the foundation to the conscious unitary sense of self. Correspondingly, this central representation of internal state is relevant to understanding the expression of psychological symptoms and behaviours and ultimately psychiatric disorders. Here we review interoception, particularly from a cardiovascular perspective, and how understanding theoretical neural and psychological aspects of interoception relates to perceptions, thoughts, and feelings. We examine how perturbations in interoceptive processing are expressed in mental symptoms and psychiatric disorders and show how this knowledge may yield new treatment targets.