This study aimed to ascertain the contribution of children's effortful control (EC) to math achievement by testing the mediational involvement of math anxiety. Participants were 704 children (367 girls) aged between 7 and 12 years (M = 9.43, SD = 1.23). Children's EC was measured by parent's report, math anxiety was assessed through self-report, whereas math achievement was evaluated by performance on standard math tests. The models tested involved EC higher-order factor or specific EC components (activation control, attentional focusing, and inhibitory control). The results showed that activation control, attentional focusing, and EC higher-order factor contributed to math performance directly and through the mediation of math anxiety. Inhibitory control did not yield a significant effect on math performance. The findings suggest that children with higher dispositional effortful self-regulation tend to experience lower levels of math anxiety, with positive effects on math performance.