Lattice disorder engineering on highly crystalline texture toward high-efficiency N2-to-NH3 electrocatalysis is tremendously challenging. Here, abundant lattice disturbances were established on an ultrafine Nb2O5 nanoparticle by Cu substitution. Cu-Nb2O5 anchored on a carbon material (Cu-Nb2O5@C) exhibits excellent activity and high selectivity for N2 electroreduction to NH3 with a yield rate of 28.07 μg h-1 mg-1 and a faradaic efficiency (FE) of 13.25% at -0.2 V vs. reversible hydrogen electrode (RHE) in acidic electrolyte. Cu-Nb2O5@C presents superb durability with no obvious change in catalyst constituents and structure after N2 reduction as confirmed by ex situ characterization studies. The excellent catalytical performance should originate from structural superiority of lattice turbulence for more active sites and optimized electronic state as well as good conductivity of carbon support. Meanwhile, in neutral electrolyte, the NH3 FE also reaches up to 10.29% at the same potential.