High-pressure researches on nanostructured materials have been of considerable interest owing to the quantum confinement effect and intrinsic defects in the nanocrystals. Here, we report a pressure-induced reversible structural phase transition in nanostructured Bi2Te3 hierarchical architectures (HAs) that were prepared via a facile solution-phase method. Therein, distinct phases I-IV by respectively adopting crystal structures of rhombohedral (I), monoclinic (II, III) and cubic (IV) were experimentally identified with increasing pressure up to 20.2 gigapascals (GPa) in a diamond anvil cell (DAC). It is worthwhile to notice that nanostructured Bi2Te3 HAs ultimately evolved into a fascinating Bi-Te substitutional nonmetallic alloy at pressure even as low as 15.0 GPa, approximately 10 GPa lower than that of the corresponding bulk counterpart. Synergistic effect involving large volume collapse and the unique one-dimensional nanostructures with intrinsic antisite defects was proposed to be responsible for the reduction of transition pressure that is contrary to the general model for most nanomaterials. Our findings may pave a potential pathway for developing future multifunctional nanoalloys that are composed of nonmetallic elements.