<p>Emotion is inevitably present in almost every action that learners and teachers take in the L2 classroom. More specifically, English as foreign language (EFL) learners experience various emotions—pleasant or unpleasant—the regulation of which can contribute to the effectiveness of their skill performance. Despite the surge of interest in emotion regulation (ER) in language education, research on how ER affects EFL learners’ oral performance, especially in emotionally-loaded speaking tasks, is surprisingly underrepresented. To address this void, the current mixed-methods study investigated EFL learners’ performance in emotionally-loaded speaking tasks after receiving a six-week ER training intervention. Prior to the intervention, a proficiency test was administered to the participants for the purpose of homogenization. Semi-formal interviews, along with demographic questionnaires, further ensured their previous non-participation in psychology-related courses. The final sample (<i>N</i> = 59) were assigned to either the experimental group or the control group. The results revealed that the experimental group, who received the ER intervention, performed significantly better on emotionally-loaded speaking tasks—in linguistic/discoursal accuracy, interactive communication, and emotional mastery. The findings from stimulated recall interviews with participants further confirmed the actual recruitment of ER strategies by participants who received the intervention and their effectiveness in emotionally-loaded speaking tasks.</p>