Abstract: Whether digital agricultural extension promotes farmers’ adoption of scientific fertilization technologies is an important question in advancing agricultural green transformation in the context of digital rural development. Based on survey data from 707 grain-growing households in Henan Province in 2025, this study uses an ordered Probit model to examine the effect of digital agricultural extension on farmers’ adoption of scientific fertilization technologies. The results show that: 1) Greater exposure to and use of digital agricultural extension methods are significantly associated with farmers’ adoption of scientific fertilization technologies. Each additional digital extension method that farmers are exposed to or use reduces the probability of non-adoption by 9.4 percentage points and increases the probability of adopting two categories of technologies by 7.4 percentage points. 2) Instrumental variable estimation, propensity score matching, and robustness tests support these findings. 3) When the four extension methods are included in the model separately, the estimated coefficients for all four methods are significantly positive. When they are included simultaneously, the coefficients for digital information push and online consultation remain significantly positive. 4) Mechanism analysis reveals significant indirect effects through both perceived ease of use and perceived usefulness, with perceived ease of use having a larger estimated indirect effect and mediation proportion. 5) Heterogeneity analysis reveals differences in the effects of digital agricultural extension according to farmers’ educational attainment and mechanization conditions. Therefore, agricultural extension organizations should develop accessible and interactive digital services to reduce the difficulty of technology adoption and tailor extension approaches to farmers’ individual characteristics and production conditions.