Learners can experience mixed emotions simultaneously. This study identified the emotion clusters based on positive activated (e.g., energetic) positive deactivated (e.g., calm), negative activated (e.g., angry), and negative deactivated (e.g., fatigued) emotions experienced by students in academic situations. We also examined differences in behavioral engagement, cognitive engagement, disengagement, and academic achievement among the derived emotion clusters. A total of 159 undergraduate students enrolled at a university in the Seoul metropolitan area participated in this study. As results, first, four different emotion clusters were identified: Positive (37%), Negative (16%), High-Mixed (31%), Moderate-Mixed (16%) clusters. Second, there were significant differences in the level of class engagement among the four clusters, with the Positive cluster generally showing a higher level of class engagement and the Negative cluster showing a lower level of class engagement. The High-Mixed cluster showed a similar level of class engagement to the Positive cluster but also displayed a higher level of disengagement. However, there were no significant differences in academic achievement according to the emotion clusters. This study empirically confirms that undergraduate students in academic situations often feel mixed rather than singular affects, through person-oriented analysis. Additionally, by examining the relations between the emotion clusters and academic-related variables, this study provides implications on which emotions should be educationally supported to enhance learning experiences.