Background: Adolescence is crucial for nurturing motivation in peer relationships and for academic achievement. Although social and academic intrinsic values develop together, the direction of their development remains inconclusive. Aims: This study examined the longitudinal relations between social and academic intrinsic values to clarify their associations and directionality. Sample: A cohort of fifth-grade students in South Korea (n = 7324; 50.5% female) was followed annually through 12th grade using a nationally representative dataset. Method: Using a random intercept cross-lagged model, reciprocal relations between social and academic intrinsic values from fifth to 12th grade were analysed. Results: At the between-individual level, the association between social and academic intrinsic value was strong and positive. At the within-individual level, significant reciprocity was observed from grades 5-6 and 8-11. However, the reciprocal relation between the two variables was less evident during middle school. Across all the grades, a significant relation was found between previous academic intrinsic values and subsequent social intrinsic values. Conclusions: This study confirmed the positive association between social and academic intrinsic values among South Korean adolescents, suggesting they often develop hands-in-hand. Reciprocal effects were notable during early adolescence, with enjoyment in one domain closely linked to enjoyment in another. This effect weakened during middle school, but strengthened during high school, suggesting a shift in priority or social dynamics at different developmental stages. These findings highlight the importance of considering developmental stages in social and academic motivation research.