Objective: Patients receiving ambulatory forensic care often present with cognitive dysfunction. Accommodating this in treatment first requires a better understanding of patients’ cognitive characteristics. Therefore, we investigated whether forensic psychiatric outpatients differed from healthy controls in their performance on a cognitive screen, the Montreal Cognitive Assessment (MoCA). Furthermore, we examined which of its subtests were relatively more affected in forensic psychiatric patients who performed above the cut-off score (i.e., low-probability group) relative to those that performed below the cut-off score (i.e., high-probability group) on the MoCA. Method: MoCA scores were extracted from a pre-existing data set for 112 forensic psychiatric outpatients and 210 healthy controls, and group comparisons were conducted. Results: Forensic outpatients had significantly lower performance on the subtests targeting executive functioning, attention, concentration, working memory, and orientation compared to cognitively unimpaired controls. Within the forensic group, the patients with a higher probability of exhibiting cognitive decrements performed relatively worse in all neurocognitive domains. Conclusions: The results suggest that, in particular, the cognitive domains of executive functioning, attention, memory, and orientation should be routinely assessed as part of neuropsychological testing in forensic psychiatric settings. Our study offers a step toward the use of neuropsychological measurements in the refinement of diagnosis and treatment in forensic psychiatry.