In the context of the “dual carbon” goal, agricultural planting is a significant source of greenhouse gas emissions, and quantifying its carbon footprint is crucial for formulating effective carbon emission reduction strategies. This study measures the carbon emissions, carbon absorption, and carbon footprint of agricultural planting activities in Hunan Province from 2006 to 2020. Using the Theil index model, we reveal the spatiotemporal heterogeneity of the planting industry’s carbon footprint, while the LMDI model is employed to conduct an in-depth analysis of its driving factors. The results show that the total carbon emissions, carbon absorption, and carbon footprint of Hunan’s planting industry exhibited a fluctuating trend, initially increasing and then decreasing, while carbon footprint intensity showed a continuous decline. The primary sources of carbon emissions were chemical fertilizer application and farmland utilization, accounting for 77.76% and 9.51% of total emissions, respectively. Carbon absorption was predominantly contributed by rice cultivation, accounting for 80.7%. Among the different regions, the Dongting Lake area had the highest carbon emissions, carbon absorption, and total carbon footprint, whereas the Greater Western Hunan area exhibited the highest carbon footprint intensity. The Theil index analysis indicates that the overall disparity in carbon footprint intensity has shifted from inter-regional differences to intra-regional differences, with the Changsha-Zhuzhou-Xiangtan area contributing the most to regional disparities, while intra-regional differences in the Dongting Lake area have expanded annually. The LMDI decomposition analysis reveals that improving agricultural production efficiency is the key factor in mitigating the growth of the planting industry’s carbon footprint, whereas the rising agricultural economic level has, to some extent, exacerbated carbon footprint growth. This study proposes a series of policy recommendations, including enhancing resource utilization efficiency, optimizing the allocation of production inputs, and adjusting the agricultural industrial structure. These findings provide valuable insights for formulating precise carbon emission reduction policies for the planting industry in Hunan Province.