Background Research suggests that enhanced neural reactivity to errors, measured via the error‐related negativity (ERN), is relatively unique to internalizing psychopathologies (IPs) and symptom clusters characterized by excessive worry and apprehension. However, no prior study has tested the association between the ERN and IP symptom dimensions in a heterogeneous, clinically representative patient population. The current study was designed to address this gap in the literature and clarify the role of the ERN in an adult IP treatment‐seeking patient sample. Method Eighty‐five participants completed a well‐validated flanker task known to robustly elicit the ERN and a battery of questionnaires assessing a range of IP symptoms. All participants had at least one IP diagnosis and over 75% had co‐occurring IPs. A principal components analysis (PCA) was performed on the questionnaire data indicating two distinct factors that characterized the IP sample: affective distress/misery and fear‐based anxiety. Results Analyses indicated that within this sample, an enhanced ERN, but not CRN, was associated with greater fear‐based anxiety symptoms but had no relation with distress/misery symptoms. Conclusions Together, these findings indicate that an enhanced ERN may not be specific to worry/apprehension and may extend to the IP fear dimension. The results also converge with a broader literature suggesting that fear‐based psychopathology is characterized by an exaggerated reactivity to threat and this objective, psychophysiological response tendency may distinguish fear disorders from distress.