The maturation of processes involved in performance monitoring, crucial for adaptive behavior, is a core aspect of developmental changes. Monitoring processes are often studied through the analysis of error processing. Previous developmental studies generally focused on post-error slowing and error-related EEG activities. Instead, the present study aims at collecting indicators of error monitoring processes occurring within trials that is, before the erroneous response is produced. Electromyographic (EMG) activity and force produced during responding were registered in 6 to 14-year-olds performing a choice-response task. As already reported in adults, force produced was weaker, EMG bursts were smaller, and motor times (interval between EMG onsets and responses) were longer during errors compared to correct responses. In contrast, the rising part of EMG burst, reflecting the initial motor command, was the same for both response outcomes. This suggests that error inhibition was applied online after the response was triggered but before the actual key was pressed. This error correction was already present in children as young as 6 years old. The effects of reduced EMG and force amplitudes remained stable across childhood. However, the prolonged motor times in young children suggests that they need more time to implement motor inhibition than their older peers.