The L2 motivational self-system (L2MSS) has been extensively investigated in multiple contexts. However, few studies have explored its correlation with Islamic junior high English students’ proficiency test results. To fill the void, this study examines the relationship between the L2MSS and English proficiency test scores among Indonesian Islamic junior high school students. Data were garnered quantitatively from 30 students of an Institute for Foreign Language Development at an Indonesian private university through a questionnaire and an English proficiency test and then were analyzed using the SPSS software system. The findings revealed that the correlation between motivation and achievement was statistically insignificant. We obtained the score of three components; ideal L2 self (r = .01, p .05), L2 learning experience (r = -.204, p .05), and ought to L2 self (r = -.343, p .05). The findings suggest that the ideal L2 self showed a very low relationship and the other two demonstrated a negative direction correlation. This study contributes insights into the understanding of the correlation between foreign language learning motivation and its influence on achievement in the Islamic boarding school context. Further research could recruit participants from wider areas with different contexts.