This research examined whether prevalent preperformance (Study 1) and in-game (Study 2) emotions were associated with cognitive interference (i.e., thoughts of escape, task-irrelevant thoughts, and performance worries) and whether any effects were moderated by reappraisal and self-confidence. In Study 1, team-sport players’ preperformance anxiety positively, and excitement negatively, predicted cognitive interference during a competitive match. However, no moderating effects for reappraisal or confidence were revealed. In Study 2, badminton players’ in-game anxiety, dejection, and happiness positively predicted, whereas excitement negatively predicted, cognitive interference during a competitive match. Moreover, reappraisal and confidence moderated the relationships of excitement and happiness with task-irrelevant thoughts. The findings underscore the role that preperformance and in-game emotions can play in athletes’ thought processing during sport performance, as well as highlighting the importance of considering the effects of self-confidence and reappraisal on the role of in-game emotions in cognitive interference.