Traumatic brain injury is prevalent and linked with heightened risk for post-traumatic stress symptoms, yet little research has investigated the role of well-established cognitive-affective risk factors in explaining this association. The present study addressed this gap by evaluating if elevations in anxiety sensitivity global score and subscales (cognitive concerns, physical concerns, social concerns) potentiated the effects of traumatic brain injury history on post-traumatic stress symptoms in two clinical samples: trauma-exposed smokers (n = 256; study 1) and trauma-exposed treatment-seeking adults (n = 117; study 2). Both samples revealed a significant interaction such that traumatic brain injury was more strongly linked with post-traumatic stress symptoms among those with high anxiety sensitivity cognitive concerns. In addition, anxiety sensitivity cognitive concerns demonstrated a stronger relationship with post-traumatic stress symptoms among those with a traumatic brain injury history. Taken together, these results of both studies underscore the importance of anxiety sensitivity cognitive concerns in the association of traumatic brain injury and posttraumatic stress symptoms.