<p>Though there is a considerable amount of research on teachers’ emotions and emotion regulation strategies, scant attention has been paid to research supervisors. The current research explored the emotions and the emotion regulation strategies employed by four undergraduate thesis supervisors in two contexts: one top national key university and one applied-oriented university. Multiple sources of data were collected, including semi-structured interviews with supervisors, observation of supervision meetings, and supervisory written feedback on thesis drafts. The findings indicate that these undergraduate supervisors mainly experienced negative emotions, and they were able to regulate emotions by multiple regulation strategies. While supervisors at the national key university employed more strategies of the antecedent-focused approach, such as prevention and intervention, supervisors at the applied-oriented university appear to be more reliant on the response-focused approach, for example, suppression. Pedagogical implications for students’ supervision and teacher education were proposed to improve supervisors’ emotions and enhance their emotion regulation competence in research supervision.</p>