Improving others’ emotions is cognitively and emotionally demanding, potentially increasing regulators’ stress levels and decreasing regulators’ wellbeing. However, it is also reasonable to expect that the opposite could occur: Engaging in affect-improving extrinsic interpersonal emotion regulation (EIER) may enhance regulators’ affective wellbeing and shield against stress because affect-improving EIER can also activate regulators’ emotion regulation and foster better social interactions. In two studies, we test the intrapersonal consequences of engaging in affect-improving EIER. In Study 1, a 7-day diary study (N = 205; 1434 observations) of most significant social interactions, regulators who improved the emotions of others experienced an increase in positive affect from day 1 to day 7 and better wellbeing at the end of the study. In Study 2, a laboratory study (N = 102, 51 dyads), attempts to improve an interaction partner’s emotions were associated with the alleviation of physiological stress measured by pre-ejection period (PEP) reactivity. These findings empirically support the role of affect-improving extrinsic interpersonal emotion regulation in the self-regulation of emotions and contribute to the theoretical understanding of why social relationships are important for overall health and wellness.