A consistent amount of research has tried to study the contributions of cognitive and emotional factors involved in math achievement. Despite this, research examining their joint role in children is scarce. In this paper, we examined the joint role of cognitive and math anxiety on math achievement in a sample of 135 seventh-grade children (54% male, M-age = 12.79, SD = 0.47). Math achievement was measured using a validated paper-and-pencil test, while higher-order cognitive abilities were assessed with a PMAs test. Working memory was evaluated through two verbal and two visuo-spatial experimental span tasks. Inhibitory control was measured using three computerized tasks adapted from the classic Stroop, Flanker, and Simon tasks. Math anxiety was assessed with an AMAS questionnaire. A series of correlation analyses and path models were conducted to understand the complex relationships among the factors. The correlations showed a positive relationship among our cognitive abilities and a negative correlation with math anxiety. The results from the path analysis showed a strong effect of higher-order cognitive abilities on math achievement (beta = 0.44, p < .001) and highlighted the mediating role of working memory between math anxiety and math performance (beta = -0.04, 95%CI [-0.11; -0.00]). Conversely, inhibitory control did not seem to play a crucial role in this relationship (beta = -0.03, 95%CI [-0.08; 0.00]). These findings are discussed in relation to current theoretical frameworks. Interventions aimed at reducing math anxiety could help improve math achievement.