This manuscript aimed to advance our understanding of inhibitory control (IC) in autism spectrum disorders (ASD), adopting a meta-analytic multilevel approach. The first meta-analysis, on 164 studies adopting direct measures, indicated a significant small-to-medium (g = 0.484) deficit in the group with ASD (n = 5140) compared with controls (n = 6075). Similar effect sizes between response inhibition and interference control were found, but they were differentially affected by intellectual functioning and age. The second meta-analysis, on 24 studies using indirect measures, revealed a large deficit (g = 1.334) in the group with ASD (n = 985) compared with controls (n = 1300). Presentation format, intellectual functioning, and age were significant moderators. The effect of comorbidity with ADHD was not statistically significant. Implications are discussed for IC research and practice in autism.