Mycorrhizal fungi form symbiotic relationships with plant roots, connecting multiple plants through underground networks. This biologically based “wood wide web” facilitates resource transfers between plants and is hypothesized to act as an underground communication system. We explored mycorrhizal network dynamics in sub-tropical forests of northern Pakistan. Using isotopic tracing, DNA sequencing, and root imaging, we found mycorrhizal fungal networks transferred carbon, nitrogen, and phosphorus between trees and provided growth benefits to connected seedlings. Unexpectedly, we discovered single fungal genotypes linking trees across 2 km, demonstrating extensive network reach. Our results provide comprehensive field evidence that the World Wide Web functions as a cooperative conduit enabling plants to share resources, signaling chemicals, and defense compounds. Mycorrhizal networks appear critical for seedling establishment, kin recognition, and forest resilience. Further elucidating these complex dynamics will transform our understanding of belowground ecology and enable the application of nature’s symbiotic innovations.