The present work was initiated to investigate how technology of preparation of nanocomposites (Co₄₅Fe₄₅Zr₁₀) Z(Al₂O₃)_1-Z affects their magneto-optical (MO) properties. The spectral, magnetic field and concentration dependences of the transversal Kerr effect (TKE) have been studied either for bulk or layer-by-layer deposited nanocomposites within a wide range of the ferromagnetic (FM) phase concentrations and for various thicknesses of layers. It was found that the MO response of the layer-by-layer deposited nanocomposites with compositions inside the percolation interval differs essentially from the one of the bulk composites and depends on the layer thicknesses. With decreasing thicknesses of layers the percolation threshold has been shifted towards the lower contents of the FM phase. In addition, it has been established that the size and shape of the granules inside the nanocomposite layer also depends on the layer thickness as well as the microstructure of the layer-by-layer sputtered composites considerably differs from the microstructure of the bulk nanocomposite.