Studies have suggested cognitive flexibility as an enhancer of academic performance. However, this link has not been confirmed across diverse samples of countries, which requires a cross-cultural reinvestigation with a consideration of possible contextual moderators such as societal culture. Specifically, we consider the moderating role of societal flexibility (vs. monumentalism), a dimension from Minkov-Hofstede's cultural model which emphasizes humility, adaptability, and desire for self-improvement. Using international survey data from the Programme for International Student Assessment (PISA) 2018, this study examines the relationship between adolescents' cognitive flexibility and academic performance in diverse sociocultural contexts. Results from multilevel analyses of 378,087 adolescents from 57 countries show that adolescents' cognitive flexibility is positively associated with academic performance in a global context. An interaction term, however, reveals that the academic benefits of adolescents' cognitive flexibility are significantly greater in more flexible societies. In addition, we identify individual and cross-national characteristics that influence adolescents' academic performance such as gender, socioeconomic status, national wealth, and educational level. These findings reveal the role of individual factors on adolescents' academic performance and emphasize the importance of the interaction between individual and sociocultural factors.