The error-related negativity (ERN) is a negative wave observed in electroencephalography (EEG) following errors in certain neurocognitive tasks, such as the Flanker task. This wave has been found to be heightened in individuals suffering from obsessive–compulsive disorder (OCD) in several adult studies and meta-analyses. Therefore, the ERN may serve as a relevant neurobiological marker for OCD. However, the ERN exhibits some developmental aspects. Considering this, we conducted a meta-analysis of studies examining the ERN in children and adolescents with OCD. We identified nine studies that compared ERN amplitude during a Flanker task between youth with OCD and matched controls. Our meta-analysis revealed that ERN amplitude was elevated in juvenile OCD patients compared to controls. We did not find that age, task accuracy, or sex moderated the difference between patients and controls. In conclusion, our meta-analysis confirmed that the ERN observed during the Flanker task may be a relevant biological marker for OCD in children and adolescents.