Interoception describes the ability to perceive internal bodily signals. Previous research found a relationship between interoceptive accuracy (IAcc) and cardiovascular outcomes during or after acute stress. So far, the association between IAcc and long‐term stress has not been investigated, although this would be important to identify a starting point to prevent long‐term stress. To address this idea in the current study, we examined the relationship between IAcc and long‐term stress, which was assessed with different questionnaires and biological markers, including cortisol and dehydroepiandrosterone (DHEA). Furthermore, we investigated self‐regulation as a mechanism linking IAcc to long‐term stress. The sample consisted of 98 participants. To measure IAcc, participants completed the heartbeat perception task. Perceived long‐term stress and self‐regulation were assessed via an online questionnaire. Moreover, hair samples were taken from 65 participants to determine long‐term stress with cortisol and DHEA as well as the ratio of both. Results showed that IAcc was positively related to DHEA and weakly negatively related to the other indicators of long‐term stress, except for the nonsignificant relationships to the indicators cortisol and stress experiences due to negative events. Furthermore, these relationships were mediated by participants' enhanced self‐regulation. Thus, our results suggest that enhanced self‐regulation could be a mechanism explaining why IAcc is associated with long‐term stress.