The literature on passion reveals that harmonious passion (HP) leads to more positive emotions than obsessive passion (OP), whereas the opposite is obtained with negative emotions. This research aimed to evaluate the role of cognitive appraisals (CA) as mediators of passion-emotion relationships. This hypothesis implies that HP is linked to challenge appraisals that, in turn, are associated with positive emotions. Also, OP is expected to be linked to threat appraisals that, in turn, are associated with negative emotions. In Study 1, 227 participants engaged in different sports completed an online questionnaire. Results from structural equation modeling analysis provided support for the proposed sequence involving passion, CA, and emotions. In Study 2, 155 athletes completed questionnaires before and after a competitive game. Results of analyses conducted separately in success and failure conditions supported the hypothesized sequence in defeat for both types of passion, and in victory for HP only. OP was indeed not linked to threat appraisals among victorious athletes. These results suggest that both types of passion trigger different CA that lead to the corresponding emotions. Future research is needed to replicate these findings and to better understand the role of passion and CA in emotions experienced in sports.