Presurgical psychological assessment of bariatric surgery candidates aims to identify psychosocial risk factors and provide treatment recommendations to facilitate optimal outcomes. Such assessment typically includes psychometric testing and a clinical interview. The Minnesota Multiphasic Personality Inventory (MMPI) has been commonly used as a broadband measure to assess a number of psychosocial domains in bariatric clinics. The newest version of the MMPI, the MMPI-3, was recently released. This study sought to (1) establish whether the MMPI-3 is comparable to the MMPI-2-RF in a sample of patients seeking bariatric surgery, (2) report reliability data for all MMPI-3 scale scores in this sample, and (3) explore associations between commonly used self-report symptom measures and substantive scales of the MMPI-3 to ascertain convergent and discriminant validity patterns. Six hundred and thirty-five presurgical patients completed the MMPI-3 in addition to the Patient Health Questionnaire-9 (PHQ-9), General Anxiety Disorder-7 (GAD-7), Alcohol Use Disorders Identification Test-Consumption (AUDIT-C), and Eating Disorder Examination-Questionnaire (EDE-Q). The majority (79.1%) of the sample was female, 65.5% was white, and 26.6% was Black. Scores on most of the MMPI-3 Emotional/Internalizing Dysfunction scales were meaningfully associated with the PHQ-9, GAD-7, and most EDE-Q subscales (except for Restraint). Meaningful discriminant patterns were observed as well. We conclude that the substantive scales of the MMPI-3 are reliable, comparable to their MMPI-2-RF counterparts, and evidence good convergent validity with extra-test measures assessing depression, anxiety, alcohol use, and eating disorder psychopathology in a preoperative bariatric sample.