Objectives: This study evaluated the psychometrics of the Farsi translation of diagnostic interview for attention-deficit hyperactivity disorder (ADHD) in adults (DIVA-5) based on DSM-5 criteria. Methods: Referrals to a psychiatric outpatient clinic (N = 120, 61.7% males, mean age 34.35 ± 9.84 years) presenting for an adult ADHD (AADHD) diagnosis, were evaluated using the structured clinical interviews for DSM-5 (SCID-5 & SCID-5-PD) and the DIVA-5. The participants completed Conner’s Adult ADHD Rating Scale-Self Report-Screening Version (CAARS-S-SV). Results: According to the SCID-5 and DIVA-5 diagnoses, 55% and 38% of the participants had ADHD, respectively. Diagnostic agreement was 81.66% between DIVA-5/SCID-5 diagnoses, 80% between SCID-5/CAARS-S-SV, and 71.66% between DIVA-5/CAARS-S-SV. Test–retest and inter-rater reliability results for the DIVA-5 were good to excellent. Conclusion: Findings support the validity and reliability of the Farsi translation of DIVA-5 among the Farsi-speaking adult outpatient population.