With 428 described species, Old World tree frogs (rhacophorids) form a spectacular diversification spanning a climatically variable region across much of mainland Asia, nearby islands, and parts of Africa. Their diversification, particularly in relation to their climatic niche, remains poorly understood, mostly due to incomplete data and taxon sampling. Hence, we provide a complete, species-level phylogeny of all extant rhacophorids by integrating phylogenomic/Sanger sequence data and phylogenetic imputation to delineate patterns of their diversification. Lineage-Through-Time plots show a constant rate of diversification with a slight increase towards present. We determine rates of diversification and spatial variation in distribution of species and delineate spatiotemporal variation showing high species accumulation in rainforest habitats around Borneo, peninsular Malaysia, Vietnam, Yunnan (China), Western Ghats and Sri Lanka. Climatic niche and phylogeography analyses explain how spatial and temporal structuring is shaped by the evolution of their climatic niches. We highlight cool-wet regions and islands being associated with regions of high species accumulation hence contributing towards generation and maintenance of their diversity; knowledge vital for their conservation. Further, a higher disparity of climatic niche evolution is evident since Eocene-Oligocene transition – species in East/Southeast Asia, Himalaya evolved towards colder climatic conditions while species inhabiting Sundaland and Peninsular India evolved towards warmer climatic conditions.