The error-related negativity (ERN) is an electrophysiological response to errors. Individual differences in the ERN have been posited to reflect sensitivity to threat and linked with risk for anxiety disorders. Attention bias modification is a promising computerized intervention that has been shown to decrease threat biases and anxiety symptoms. In the present study, we examined the impact of a single session of attention bias modification, relative to a control task, on the neural correlates of response monitoring, including the ERN, correct response negativity (CRN), and their difference (i.e., the ERN – CRN or ΔERN). The final sample included 60 participants who first completed a flanker task to elicit the ERN and CRN, and were then randomly assigned to attention bias modification (n = 30) or a control task (n = 30). After completing the attention bias modification or control task, participants completed the same flanker task to again elicit the ERN and CRN. Among participants who completed attention bias modification training, the ERN, CRN, and ΔERN decreased from the pre- to post-training assessment. In contrast, in participants who completed the control task, the CRN, ERN, and ΔERN did not differ between the pre- and post-training assessment. The presents study suggests that a single session of attention bias modification reduces neural correlates of response monitoring, including error-related brain activity. These results also support attention bias modification as a potential mechanistic-based intervention for the prevention and treatment of anxiety pathology.