Popularity has been empirically linked to psychological and several indices of school adjustment outcomes during childhood and early adolescence. Yet, best friend popularity in relation to the adjustment outcomes remains unclear, especially in more interdependent-oriented cultures. To address this gap, this study applied the Actor-Partner Interdependence Model (APIM) to simultaneously considering whether, and how, the popularity of youth (actor effects) and their best friends (partner effects) contribute uniquely to psychological well-being and school adjustment outcomes, after controlling for social preference. Age and gender differences were also examined. Participants were 162 same-gender best friend dyads (81 boys, Mage = 11.24 years, SD = 1.18) from Shanghai, P.R. China. Among the results, both youth’s own and their best friends’ popularity were positively related to self-esteem and school attitudes, and negatively related to depressive symptoms. In addition, results from multi-group analyses revealed both actor and partner effects did not vary across gender. Finally, exploratory analyses showed that only actor effects varied across age for the associations between popularity and self-esteem and school attitudes. These findings highlight the important role of the best friend’s popularity in promoting Chinese youth’s experiences of psychological and school adjustment.