Droughts exert a critical impact on forest growth, posing great challenges for forest sustainability globally. However, the mechanistic role of forest height (H) in modulating drought resistance remains poorly understood. Utilizing spaceborne observations of H and solar-induced chlorophyll fluorescence as a proxy for photosynthesis, here we show that taller forests consistently demonstrate higher resistance to drought stress globally, across varying levels of drought severity. This suggests that taller forests maintain higher stability under fluctuating climatic conditions. By synthesizing global forest root data, we found that this enhanced stability is closely tied to the deeper rooting systems of taller forests. Our findings underscore the critical role of H in forest ecosystem functioning and advocate for its inclusion as a key trait in ecosystem models to improve simulations of forest responses to climate change.