There is evidence showing that the triarchic model of grit and its dimensions (i.e.,per-severance of effort, consistency of interests,andadaptability to situations) predict engagementand well-being outcomes in high school and undergraduate students during the COVID-19 pandemic outbreak. However, there has been limited research on how this model ofgrit relates to engagement and optimal psychological outcomes in primary school stu-dents. This research investigates the association of grit’s dimensions with academicengagement in math and science as well as well-being outcomes (i.e., positive emotions,negative emotions, andflourishing) in primary school students. Participants were pri-mary school students (Mage=10.42;SDage=1.26) from Hong Kong (n=279) andMacau (n=124). Results showed thatperseverance of effortpositively predicted cognitiveand behavioral engagement in math as well as positive emotions even after controllingfor demographic covariates (i.e., age, gender, setting, and year level), conscientiousness,and achievement goal orientations.Adaptability  to situationspositively predicted cognitiveand social engagement in math andflourishing.Consistency  of  interestsnegatively pre-dicted both cognitive engagement in science and negative emotions. Indeed, this studyindicates thatperseveranceandadaptabilitymay facilitate children’s positive academicand psychological functioning during the COVID-19 pandemic outbreak.