Religiousness has been proposed to promote prosociality among young people. Few investigations, however, have examined the underlying processes that facilitate these links, especially in non-Western and collectivistic societies. This study investigated the mediating role of the 5Cs (competence, confidence, connection, character, and caring) of positive youth development on the associations between religiousness, empathy, and altruism, while controlling for age and gender, among Southeast Asian emerging adults during COVID-19. Data were obtained from 1,888 emerging adults ( M age = 21.85; SD age = 2.81) from Indonesia, Malaysia, Singapore, the Philippines, and Thailand. Structural equation modeling showed that confidence, connection, and character mediated religiousness and altruism while confidence, connection, character, and caring mediated religiousness and empathy, even after controlling for the covariates. However, confidence yielded negative relations with both outcomes. The results highlight the importance of distinguishing self-oriented and other-oriented thriving characteristics in facilitating empathy and altruistic behaviors in difficult situations.