<p>Biodiversity is essential for maintaining ecosystem functionality, ensuring food security, regulating climate, and sustaining human well-being. Yet, in neglected biomes, biodiversity is often lost before many species can even be identified or studied. In Brazil, the Cerrado stands out as the most flora diverse savanna on the planet, but it remains critically underexplored. To address this gap, the National Forest Inventory (IFN) carried out an unprecedented, systematic sampling across the Brazilian Cerrado. Using 1803 tree-inventoried vegetation plots across the most biodiverse savanna on earth, we offer a first biome-wide assessment of tree diversity across the Brazilian Cerrado. We mapped tree species richness and alpha-diversity at 0.1-degree resolution and investigated their environmental drivers. Using only spatial location, stratified by vegetation formation, our LOESS-based model provides the most spatially detailed assessment of tree diversity across the Brazilian Cerrado to date, explaining approximately 47% of the observed variation in tree species richness. The south-western and central-western regions of the Brazilian Cerrado exhibited the highest tree biodiversity. Tree species richness was positively associated with broad-scale precipitation, temperature gradients, and soil clay content, whereas it declined with increasing fire frequency, soil bulk density, and soil aluminium concentration. Our results reveal marked spatial patterns and key environmental drivers of tree diversity across the Brazilian Cerrado, providing a valuable foundation for future biodiversity assessments and evidence-based conservation planning throughout the biome.</p>