This study presents a comprehensive investigation of chemical, structural, and magnetic properties of Ti/Ni multilayer systems with period thicknesses of 4 nm and 10 nm. Particular attention was paid to the characterization of the transition layers at Ni–Ti interfaces and the influence of thin silicon barrier layers on their formation. A combination of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray reflectometry (XRR), and SQUID magnetometry was employed for analysis. Extended transition layers up to 1.2 nm in thickness were identified at the Ni–Ti interfaces, primarily composed of the intermetallic Ni3Ti phase. The insertion of ultra-thin silicon buffer layers at the interfaces significantly suppressed the formation of intermetallic compounds, most likely due to the formation of titanium silicides. Additionally, it was observed that the use of Si layer on the sample surface leads to the formation of silicon oxide after exposure to the ambient environment, which acts as a passivation layer and inhibits oxidation of Ni and Ti layers within the topmost period of the multilayer structure.