This study investigates the effects of corpus use on second language (L2) vocabulary learning as well as the influence of moderators on effectiveness. Based on 29 studies representing 38 unique samples, all of which met several criteria for inclusion (e.g. with control groups), we found an overall positive medium-sized effect of corpus use on L2 vocabulary learning for both short-term (77 posttest effect sizes; Hedges' g = 0.74, SE = 0.09, p < 0.001) and long-term periods (34 follow-up effect sizes; Hedges' g = 0.64, SE = 0.17, p < 0.001). Furthermore, large variation in adjusted mean effect sizes across moderators was revealed. Above all, for the different dimensions of L2 vocabulary knowledge, in-depth knowledge (i.e. referential meanings as well as syntactic features of vocabulary) was associated with a large effect size. Moreover, the results revealed that learners' L2 proficiency and several features of corpus use (i.e. interaction types, corpus types, training, and duration) influence the magnitude of the effectiveness of corpus use in improving L2 vocabulary learning.