Background <p>Pigmentation patterns are central to animal biology—shaping camouflage, signaling, and mate selection—and uncovering the mechanisms driving their diversification is key to understanding the evolutionary principles that generate this fundamental dimension of biodiversity. Reef fishes exhibit an incredible variety of patterns, from simple spots to intricate designs. To date, the underlying evolutionary processes that govern their diversification remain unclear.</p> Results <p>Here, we investigate the relationship between pigmentation pattern diversity, species richness, and geography across six iconic reef fish families. We provide evidence for a positive correlation between pattern diversity and species richness, with a high divergence of pigmentation patterns in every biogeographic region. Then, by using a suit of phylogenetically informed comparative analyses, we demonstrate that the evolution of pigmentation patterns is characterized by a combination of rapid and constrained phenotypic diversification.</p> Conclusions <p>Overall, our findings illuminate factors that explain pigmentation pattern diversity in living reef fishes, revealing that speciation events have driven constant high levels of pigmentation pattern disparity within subclades and across globally variable reef fish assemblages.</p>