Non-financial corporate disclosure has become increasingly important in firm valuation because investors consider information beyond financial performance when assessing organizational quality, stakeholder relationships, and long-term business prospects. However, disclosure research has largely focused on conventional ESG, CSR, and sustainability measures, while culturally grounded corporate values remain underexplored. This study aims to analyze the effect of the Sundanese Values Disclosure Index (IPNK) on firm value and examine the moderating role of firm size. The study employs a quantitative approach using panel data from 70 manufacturing companies observed over the 2022–2025 period, resulting in 280 firm-year observations selected through purposive sampling. IPNK is measured using 30 indicators across five dimensions: Silih Asih, Silih Asah, Silih Asuh, Bener, and Bageur. Firm value is measured using the Price-to-Earnings Ratio (PER), while firm size is measured using total assets. Panel regression analysis using the Common Effect Model shows that IPNK and firm size have positive and significant effects on firm value, while their interaction is also positive and significant, indicating that firm size strengthens the effect of IPNK. The findings imply that culturally grounded local wisdom disclosure can provide relevant non-financial information for firm valuation.