<p>In crystalline materials, grain boundaries have been extensively studied and are acknowledged either as structural defects or as distinct phases, referred to as complexions. However, the nature of interfaces in amorphous systems, particularly whether amorphous-amorphous interfaces constitute separate phases and their structural characteristics, remains unresolved. In this study, we report a Pd₄₀Ni₄₀P₂₀ bulk granular nanostructured glass (GNG) that exhibits an interfacial structural-compositional rearrangement. The GNG was fabricated by compacting glassy Pd₄₀Ni₄₀P₂₀ nanoparticles with surface compositional segregation under a triaxial pressure of 8 GPa. The as-prepared GNG shows Pd₄₀Ni₄₀P₂₀ nanograins with Ni-enriched interfacial regions. Upon heating, the anomalous structural-compositional rearrangement occurs specifically at the amorphous interfaces, manifested by a deep exothermic peak at a temperature T_S below the glass transition temperature T_g. This structural-compositional rearrangement induces significant modifications in both compositional fluctuations and medium-range ordering, subsequently modifying the material’s mechanical properties.</p><p></p>