Studies remain controversial concerning how enjoyment, anxiety, and boredom relate to foreign language learning (FLL) achievement. There is an inadequacy of synthesis of factors addressing the debate on emotion correlations in the empirical results. Underpinned by the control-value theory (CVT) of achievement emotions, a meta-analysis is conducted to evaluate the correlation between language achievement and three emotions, namely enjoyment, anxiety, and boredom, as classified within CVT's three-dimensional taxonomy, and to explore potential moderating factors that could influence the correlation. The researchers examined 34 international studies with 83 effect sizes on the strength of the association between achievement and the three emotions. Then, moderating effects of education level, cultural backgrounds, and instruments, i.e., the Achievement Emotions Questionnaire (AEQ), the Foreign Language Enjoyment Scale (FLES), the Foreign Language Classroom Anxiety Scale (FLCAS), and Foreign Language Learning Boredom Scale (FLLBS), were analyzed. Meta-analytic results show that FLL achievement correlates with enjoyment with a medium positive effect and correlates with anxiety and boredom with a medium negative effect. Notably, the association with enjoyment is the strongest, while that with boredom is the weakest. In subgroup analyses, it is found that participants' cultural backgrounds have a moderating effect on anxiety, and emotion instruments have a moderating effect on enjoyment and anxiety. The findings provide significant implications for emotion research.