Aim: The current study attempted to assess the effect of positive emotion on post-graduate students� psychological capital (PsyCap) as well as on their academic engagement behavior. Also, the direct relationship between PsyCap and academic engagement behavior was assessed alongside the presence of Stress as a moderating variable between PsyCap and academic engagement behavior amongst post-graduate students in Malaysia. Materials and Methods: A self-administered questionnaire was used for data collection from 373 post-graduate Ph.D. students registered in various universities throughout Malaysia with a non-probabilistic sampling technique. Research respondents belonged to management, humanities, engineering, computer science, and health sciences domains, and they responded through a questionnaire copy. Statistically, structural equation modeling (SEM) was applied to evaluate confirmatory factor analysis (CFA), reliability analysis, validity analysis, measurement model, structural model, and path analysis. Furthermore, the (5000) bootstrapping approach was utilized to test the final model. Results: For the hypothesized model, our results confirmed that positive emotions had a positive and significant effect on students� psychological capita as well as on their academic engagement behavior. Further, PsyCap also had a positive and significant effect on academic engagement behavior. Our results also reported that stress as a moderating variable has a negative and deteriorating effect on the relationship between PsyCap and the academic engagement of students. Conclusion: The study�s findings support the theoretical assumption that positive emotions help individuals generate cognitive resources, which in turn help them manage their engagement behavioral requirements. However, the stress caused by their study needs may deplete their psychological resources, consequently influencing their academic engagement behavior. Interventions like personal coaching/counseling, appropriate follow-up, and flexible goal settings with other measures may help post-graduate students in achieving their daunting tasks. Copyright © 2022 Saleem, Isha, Awan, Yusop and Naji.