<p>Riparian buffers – vegetation strips retained or established along waterways – are mandated in many countries for water and soil protection, yet their role in biodiversity conservation remains unclear. Our global meta-analysis compares forested riparian buffers with converted riparian zones in human-modified landscapes across forest biomes. We find that forested riparian buffers support higher animal biodiversity than converted riparian zones at both local and landscape scales, particularly in agricultural areas. This pattern is consistent across most freshwater and riparian taxa, in both tropical and temperate regions. Forested riparian buffers also harbor, on average, 32% more reference species (i.e., species found in continuous riparian forests) than do converted riparian zones. Optimum forested buffer width estimates for species conservation are roughly an order of magnitude wider for birds and mammals (200-380 m on each river side), than for amphibians (20-50 m) and invertebrates (6-50 m). Our findings support forested riparian buffers as an important global strategy for conserving biodiversity in forest biomes.</p>