The academic achievement of students is shaped by a complex interplay of personal, familial, and environmental factors. This study makes a novel contribution to the educational and public health literature by systematically investigating how various forms and contextual dimensions of physical activity relate to students' academic achievement across diverse socioeconomic settings. Utilising the comprehensive PISA 2015 dataset and applying ordinary least squares analysis, this research investigates the consistency of these relationships across regions and countries at varying levels of development. The results revealed a positive correlation between engaging in moderate physical activity a certain number of days per week and students' achievement in math, reading, and science. Conversely, the frequency of physical education classes per week and the intensity of vigorous physical activity per week had a negative relationship on student's achievement in these subjects. These findings were found to be consistent among developed countries in various regions. Additionally, the study observed that engaging in physical activity before and after school also influenced students' academic achievement in all three subjects, although the specific relationships varied across regions. By adopting a cross-national comparative perspective, the study yields both theoretical and practical insights, highlighting the potential multiplier effects of context-specific physical activity policies on educational outcomes worldwide.