In this meta-analysis of 40 studies with 55 independent samples and 7,988 participants, we examined the relation between mathematics vocabulary (MV) and mathematics performance, and we investigated the mechanism underlying this relation. Our findings suggest that MV was moderately related to mathematics performance. Higher-order mathematics tasks that required multistep processes demonstrated a stronger correlation with MV than did foundational mathematics tasks, and this pattern remained stable across development. After partialling out comprehension skills, cognitive skills, or both, the correlation between MV and mathematics performance remained moderate and significant, with a trend showing a stronger relation between MV and higher-order mathematics tasks than between MV and foundational mathematics tasks. These findings suggest the role of MV is more than direct retrieved mathematics conceptual knowledge. MV might serve as a medium that could facilitate cognitive reasoning in mathematics learning. Implications of these findings for theories and practice of MV are discussed.