AbstractRocky desertification is a prominent ecological issue in Southwest China's karst region, ranking among the nation's three primary ecological challenges alongside soil erosion and desertification. The government initiated the Rocky Desertification Treatment Program in 2008, lacking a comprehensive evaluation of its benefits. This study evaluates the program's impact on ecosystem services over the last two decades using remote sensing, ecosystem models, and field data. The results indicated a continuous net decrease of rocky desertification, 48% in the eight southwestern provinces from 2005 to 2021. The average annual growth rate of vegetation cover reached 2.54% in key counties for rocky desertification control, significantly higher than that of all the 451 rocky desertification counties from 2016 to 2020. Additionally, ecosystem productivity increased by 35.8% in rocky desertification counties from 2000 to 2020, which is 1.34 times greater than that observed in non‐rocky desertification counties. It was found that the ecosystem service promotion after the net reduction of rocky desertification area in 2010–2020 is more significant, especially the carbon sequestration in 2010–2020 of key counties for rocky desertification control is 2.7 times than that in 2000–2010. It indicates that the rocky desertification treatment enters the stage of ecosystem service promotion on the basis of achieving rapid “greening,” leading to significant improvements in ecosystem structures and services in the karst region of Southwest China. To mitigate the risk of rocky desertification, tailored measures must be implemented considering local climate, lithology, landform types, and human–land relations for effective treatment zoning and classification.