Vegetation cover exerts a strong control on land‐atmosphere interactions. To quantify the relative effects of external forcing (climate change) vs internal forcing (anthropogenic activity) on recent vegetation change over the Tibetan Plateau (TP), we apply an eco‐hydrological diagnostic framework, developed from earlier work. We compare vegetation change during 1986‐2015 based on NDVI (Normalized Difference Vegetation Index) data with changes in environmental conditions (European Centre for Medium‐Range Weather Forecasts Reanalysis 5th‐generation, ERA5). Results show that external forcing is the dominant factor behind significant vegetation change over the southeastern TP during 1986‐2015. In the area with significant vegetation changing, 60.5%/41.5% of pixels have experienced a respective wetting/drying of climate, which in turn has supported greening/browning during 1986‐2005/1996‐2015. However, during the greening/browning transition in the latter period, the proportion of internal forcing on browning increased from 5.62% to 19.4%, indicating that anthropogenic factors are playing an increasingly role on impacting vegetation change in recent decades.