Interoceptive accuracy is thought to play a key role in mental health. However, the validity of its most frequently used measure (i.e., the Heartbeat Counting Task; HCT) has been questioned. This calls for a meta-analytic examination of associations between HCT performance and mental health. To this end, we performed a systematic review and meta-analysis on associations between HCT performance and mental disorders, symptoms, and their risk factors among adult participants. The final data set comprised 133 studies with 11 524 participants. The quality assessment indicates that research practice should be improved as, e.g., only a few studies reported sample size justification (6%), pre-registration (0.8%), and data in free access (6.8%). HCT performance was not significantly associated with trait measures of anxiety (r = 0.03), depression (r = -0.04), and alexithymia (r = -0.01). It was weakly and negatively associated with age (r = -0.11) after correction for publication bias, sex (male > female; r = -0.14), heart rate (r = -0.17), and body mass index (r = -0.11). That theoretically assumed associations between interoceptive accuracy and mental health indicators are not meta-analytically found raises further doubts about the validity, and even the very pragmatic value, of the HCT.