Smartphone addiction, as an emerging behavioral addiction, has garnered increasing attention in psychology and behavioral sciences. The widespread use of smartphones, alongside their numerous benefits, is associated with significant physical, psychological, and social consequences, affecting sleep quality, mental health, academic performance, and interpersonal relationships. The present study aimed to examine and confirm the psychometric properties of the short-form Smartphone Addiction Scale (SAS-SV) in the Iranian adult population. The study employed a descriptive–correlational design within the psychometric framework. The target population included citizens aged 18–45 in Zanjan in 2024, with 357 participants completing the online survey. Data collection instruments comprised the SAS-SV, Young’s Internet Addiction Test (IAT), and the Mobile Social Network Addiction Questionnaire. Internal consistency was evaluated using Cronbach’s alpha, and test–retest reliability was assessed over a one-week interval. Content validity was examined through expert evaluations, while convergent validity was assessed through correlations with related instruments. Construct validity was further tested using confirmatory factor analysis, and discriminant validity was examined through known-groups comparisons. Results indicated a Cronbach’s alpha of 0.86 and an intraclass correlation coefficient of 0.89, confirming high reliability. CVI and CVR values for all items were at acceptable levels, and significant correlations with related scales supported convergent validity. Confirmatory factor analysis demonstrated good model fit, and known-groups comparison showed meaningful discrimination between groups with high and low social media usage. Findings indicate that the Persian version of the SAS-SV possesses satisfactory reliability and validity, making it a suitable instrument for assessing smartphone addiction in research and clinical applications within the Iranian population. These results facilitate future studies and evidence-based interventions.