The drivers and mechanisms of the decadal change in summer precipitation over eastern China have been widely investigated. In this context, the potential impact of vegetation changes on the Qinghai–Xizang Plateau (QXP) and its associated processes remain unclear. Using the GIMMS (Global Inventory Modeling and Mapping Studies) Leaf Area Index (LAI) dataset and gridded precipitation data over China, this study investigated the relationship between the decadal increase in spring vegetation cover in the QXP and the decadal change in summer precipitation over eastern China, and the associated mechanism. The results revealed that the late-spring (May) vegetation in the QXP has undergone notable decadal changes around 2010, with LAI anomalies turning from negative to positive. Concurrently, there has been a noticeable decadal change in the summer precipitation over eastern China after 2010, with a shift from wet to dry situations over the Huaihe River basin and South China, and precipitation anomalies turning from negative to positive over Northeast China, North China, and the middle and lower reaches of the Yangtze River basin. A composite analysis of the changes in the surface energy budget over the QXP and the East Asian summer monsoon circulation showed that, as the vegetation cover in the QXP increased in the late spring after 2010, the net surface shortwave radiation increased in response to the low-albedo characteristics of vegetation, leading to an increase in the surface temperature over the QXP and consequently enhancing the upward surface sensible heat flux. The stronger spring sensible heat flux provides a stronger atmospheric heating source in the subsequent summer, intensifying and extending the South Asian High eastward. This effect is accompanied by the strengthening and westward movement of the Western Pacific Subtropical High, thereby changing the decadal summer precipitation over eastern China around 2010. Thus, this study has elucidated the important modulating role of vegetation change in the QXP on the decadal change in summer precipitation over eastern China.