Although data asset disclosure signals firms’ competitive resource advantages, whether and how data asset disclosure influences investors’ perceptions remains unclear. Using a unique dataset comprising A-share listed firms in China from 2008 to 2023, this study finds that data asset disclosure mitigates stock mispricing. Such the effect is stronger for self-use data asset disclosure than transactional ones, and for firms with higher internal control quality, media attention, and institutional ownership. Further analysis reveals that Only routine and truthful disclosure is effective, while exaggerated disclosure backfires. These findings yield important theoretical and managerial implications for firms formulating data asset disclosure strategies.