Prior expectations shape how we see the world and monitor our feelings. In particular, it has long been evident that priors and ambiguous sensory input interact to determine the course of perceptual decision-making. However, although numerous theories emphasize an important role for interoceptive inference in shaping our exteroceptive perception, there is as yet no evidence as to how visceral rhythms modulate the interaction between priors and input.Using a novel perceptual learning task, we analysed how cyclic fluctuations of visceral signals in the cardiac domain influence affective perceptual inferences. 274 participants completed the task, in which they had to learn the probabilistic associations between arbitrary visual cues and happy or angry faces of varying valence intensities while physiological signals (i.e. electrocardiogram) were recorded. This design enabled us to manipulate the sensory uncertainty of stimuli and the expected precision of prior expectations. Having tested whether sensory uncertainty, prior expectation and valence influence perceptual behaviour including reaction time, accuracy and also confidence, we then examined how the interaction between these predictors related to the cardiac cycle. We found that cardiac dynamics over the entire trial encode sensory uncertainty and valence. Furthermore, we identified effects of these behavioural indices on confidence, reaction time and accuracy. Overall, these results show that there is both top-down modulation, with visceral signals adapting to the perceived characteristics of the sensory environment, and bottom-up modulation, with the phase of visceral cycles influencing perceptual and metacognitive biases. Perceptual consciousness in the affective domain is modulated by this delicate balance.