This prospective study examined associations between cognitive functions, self-awareness, neuroimaging data, and obsessive-compulsive disorder symptomatology in a sample of 31 patients with moderate-severe Traumatic Brain Injury (TBI). Participants completed neuropsychological tests examining specific aspects of executive functioning, as well as new learning and retention. Questionnaires assessing obsessive-compulsive disorder (OCD) symptoms and obsessive-compulsive personality disorder (OCPD) traits were completed. Patients and their treating clinicians independently completed the same questionnaire to determine level of self-awareness (SA). Discrepancy scores were used as a measure of SA. Bayes factors showed strong support for the presence of a correlation between Rey Complex Figure (RCFT) strategy and the Florida Obsessive-Compulsive Inventory (FOCI) symptom scores, and moderate support for the presence of a correlation between RCFT strategy and FOCI severity scores. Overall, results indicate self report of new onset obsessions and compulsions after TBI were associated with specific executive functions rather than memory and retention. This study suggests that OCD phenomena after TBI may in part be explained by the presence of specific cognitive deficits. Accurate differential diagnosis of OCD, versus cognitive impairment masquerading as OCD after TBI, has implications for the treatment and rehabilitation of patients.