In the context of the digital transformation of government, governmental new medias are emerging as a significant force in the management of public finance. This study draws on 530,000 WeChat posts and 284,000 Weibo posts published by provincial financial and taxation departments, combined with panel data from 281 prefectural-level cities spanning from 2006 to 2022. Utilizing large language models for text analysis, along with staggered difference-in-differences and spatial difference-in-differences models, the paper investigates the impact of governmental new media—exemplified by fiscal WeChat official accounts—on the fiscal drawing capacity of local governments. The results reveal three key findings. First, the establishment of fiscal WeChat accounts has a significant positive effect on fiscal drawing capacity, enhancing both its scale and intensity. This impact is realized through three primary channels: expanding tax sources, optimizing the business environment, and strengthening public trust. Second, the improvement in fiscal drawing capacity exhibits positive spatial spillover effects; however, spillovers differ by administrative level—provincial accounts tend to generate negative spillovers, while municipal accounts yield positive ones. Third, heterogeneity analysis shows that fiscal accounts with stronger originality, more innovative formats, and focused messaging more effectively enhance fiscal drawing capacity, whereas accounts with excessive posting frequency and dispersed themes perform less effectively. Furthermore, accounts that emphasize tax policy communication and fiscal transparency demonstrate stronger positive impacts. Municipal-level fiscal accounts are especially effective in provincial capitals, fiscally independent cities, and regions with more advanced digital infrastructure, where both provincial and municipal accounts outperform their counterparts in other cities. These findings provide robust empirical support and valuable policy insights for optimizing the development and utilization of governmental new medias in local fiscal governance.