Against the backdrop of global warming, grassland degradation (GD) in arid and semi-arid regions has become a critical issue constraining ecosystem stability and socio-ecological resilience. This study aims to reveal the spatial differentiation of drivers of GD across four functional zones in Inner Mongolia-resource-oriented (RO), center-service-oriented (CSO), agro-pastoral-oriented (APO), and ecological-oriented (EO)-at the county level, using grassland conversion processes as a structural proxy. The results show that land cover changed in 19.29%, 18.69%, 17.28%, and 4.67% of the RO, CSO, APO, and EO regions, respectively, with GR mainly occurring in the RO region, while GD was more prevalent in the other zones. Drivers of GD exhibit significant variations across functional zones. In the RO zone, land use change is primarily associated with human disturbance. In the CSO and APO zones, it is associated with human activities, climatic factors, and urbanization. In the EO zone, the identified drivers show strong spatial heterogeneity, with urbanization, grazing intensity, and climate change emerging as key associated factors in the Hulunbuir, Xilingol, and Arxar regions. Overall, the results reveal a spatial gradient in the relative importance of anthropogenic pressure and climatic stress, with broader implications for adaptive and place-specific dryland governance under ongoing warming and increasing aridification.