Abstract: Enhancing Agricultural Green Total Factor Productivity (AGTFP) has become a key issue in promoting green agricultural transformation under the goals of carbon peaking and carbon neutrality, as well as high-quality development. Based on panel data from 30 Chinese provinces from 2013 to 2022, this study employs a fixed-effects model to empirically examine the impact of open innovation on AGTFP. It further explores the underlying mechanisms using mediation analysis, moderation analysis, and threshold regression models. The results reveal that: 1) Open innovation significantly improves AGTFP, with stronger effects observed in regions with stricter environmental regulations and higher levels of urbanization. The impact also varies across eastern, central, and western regions, showing a clear gradient. 2) The research and development capacity of agricultural entities is an important mediating pathway through which open innovation enhances AGTFP. 3) The effect of open innovation on AGTFP exhibits a distinct nonlinear pattern, with dual threshold effects identified in both technological progress and technical efficiency. Based on these findings, it is recommended to strengthen the open innovation mechanism, stimulate technological progress in agricultural enterprises, improve incentive-based environmental regulation systems, and develop region-specific green development strategies to fully realize the enabling potential of open innovation in advancing AGTFP.