The impact of zinc incorporation on the chemical composition of electroless Ni-Zn-P coatings and the elements distribution through the thickness was studied. Ni-Zn-P alloy was deposited on various metal substrates (Al, Fe, Au) with and without electroless Ni-P underlayer. The employed bath formulation and the substrates with a Ni-P intermediate layer allowed direct comparison between the binary Ni-P and Ni-Zn-P alloy coatings. A reduction in phosphorus content and deposition rate due to zinc inclusion was observed. Some physical characteristics (morphology, structure, magnetic properties) of Ni-Zn-P coatings were assessed in parallel with those of M-P. The localization of Zn mainly at the grain boundaries together with P was proved by transmission electron microscopy combined with energy dispersive X-ray analysis system. The particular role of the steel substrate is discussed as a source of iron, subsequently included in electroless Ni-P and Ni-Zn-P coatings.