Summary Understanding the complex interactions between trees and fungi is crucial for forest ecosystem management, yet the influence of tree mycorrhizal types, species identity, and diversity on tree‐tree interactions and their root‐associated fungal communities remains poorly understood. Our study addresses this gap by investigating root‐associated fungal communities of different arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) tree species pairs (TSPs) in a subtropical tree diversity experiment, spanning monospecific, two‐species, and multi‐species mixtures, utilizing Illumina sequencing of the ITS2 region. The study reveals that tree mycorrhizal type significantly impacts the alpha diversity of root‐associated fungi in monospecific stands. Meanwhile, tree species identity's influence is modulated by overall tree diversity. Tree‐related variables and spatial distance emerged as major drivers of variations in fungal community composition. Notably, in multi‐species mixtures, compositional differences between root fungal communities of AM and EcM trees diminish, indicating a convergence of fungal communities irrespective of mycorrhizal type. Interestingly, dual mycorrhizal fungal communities were observed in these multi‐species mixtures. This research underscores the pivotal role of mycorrhizal partnerships and the interplay of biotic and abiotic factors in shaping root fungal communities, particularly in varied tree diversity settings, and its implications for effective forest management and biodiversity conservation.