Restoration of tropical landscapes through the expansion of secondary forests is crucial for climate change mitigation and offers co-benefits for biodiversity. However, the strength of these benefits is influenced by the position of these secondary forests within the landscape. Recovery of both carbon stocks and biodiversity in secondary forests are enhanced by proximity to old-growth forests, and old-growth forests may benefit from secondary forests in return through buffering of edge effects and reduced fragmentation. However, to date there has been no biome-wide assessment of secondary forest location relative to old-growth forests. We mapped Amazonian secondary forests and explored their proximity to old-growth forests of different conditions. We then calculated the extent to which secondary forests buffer old-growth edge forest (