This study investigates how digital transformation affects public sentiment toward firms on social media platforms in China. Using 2008-2022 data on Chinese listed companies and multivariate regression analysis, this paper identifies that digital transformation boosts positive online comments and sentiment. This relationship is mediated by gains in total factor productivity from digital initiatives. Moreover, concurrent green transformation positively moderates the effect, amplifying the impact of digital moves on online positive sentiment. Heterogeneous results reveal that the digital transformation effect on online positive sentiment is greater for state-owned, high-tech, and large companies. To our knowledge, this is the pioneering study to examine the linkage between corporate digital transformation and online public sentiment. The findings reveal whether, how, and when digital transformation shape more favorable public sentiment and online buzz. Companies can leverage digitalization, productivity improvements, and green development to foster positive perceptions and enhance their online reputation.