$Ab initio$ molecular dynamic approach is applied to analyse the amorphization process in Ni–Zr system with the control both the atomic-structure evolution and the electronic-spectra changes. The atomic positions in the Ni$_{21}$Zr$_{11}$ supercell are modelled by simulating annealing by the density functional theory in the generalized gradient approximation. Changes in the histogram of interatomic distances of the Ni$_{21}$Zr$_{11}$ supercell under ‘crystal–liquid–amorph’ phase transitions are discussed. As shown, significant variation in the local environment of the atoms (up to 30% of the mean value within the first co-ordination sphere) leads to a marked variation in the local electronic spectra for the ‘amorphous’ phase. The inapplicability of the Nagel–Tauc electronic criterion for the case of Ni–Zr-based amorphous alloys demonstrating the highest thermal stability is proved.