The perception of visceral signals plays a crucial role in many theories of emotions. The present study was designed to investigate the relationship between interoceptive awareness and emotion-related brain activity. 44 participants (16 male, 28 female) first underwent a heartbeat perception task and then were categorised either as good (n = 22) or poor heartbeat perceivers (n = 22). A total of 60 different pictures (pleasant, unpleasant, neutral) from the International Affective Picture System served as emotional stimuli. EEG (61 electrodes) and EOG were recorded during slide presentation. After each slide, the subjects had to rate emotional valence and arousal on a 9-point self-report scale. Good heartbeat perceivers scored the emotional slides significantly more arousing than poor heartbeat perceivers; no differences were found in the emotional valence ratings. The visually evoked potentials of good and poor heartbeat perceivers showed significant differences in the P300 and in the slow-wave latency ranges. Statistical analyses revealed significantly higher P300 mean amplitudes for good heartbeat perceivers (averaged across all 60 slides) than for poor heartbeat perceivers. In the slow-wave range, this effect was found for affective slides only. Heartbeat perception scores correlated significantly and positively with both the mean arousal rating as well as with the mean amplitudes in the P300 time window and the slow-wave window. Our results demonstrate a strong relationship between the perception of cardiac signals and the cortical processing of emotional stimuli, as would be postulated for example by the James-Lange theory of emotions.