The mechanical and optical properties of Si and TiO2-Si nanopillars (NPl) were investigated. Mesoporous silicon NPl arrays were fabricated by metal-assisted chemical etching and nanosphere lithography, and then pillars were covered by TiO2 using the atomic layer deposition technique. We performed scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, reflectance, photoluminescence (PL) spectroscopy and nanoindentation to characterize the as-prepared and annealed TiO2-Si NPl. The main structural and mechanical parameters of TiO2-Si NPl (grain size, strain, critical load, elastic recovery and Young’s module) were calculated. Reflectance and PL spectroscopy were used to study the impact of morphology on optical properties of TiO2-Si NPl before and after annealing. It was established that the nanostructures of TiO2 penetrated inside the porous matrix of Si pillar improve the mechanical properties of TiO2-Si NPl. The results of nanoindentation study have shown that Young’s Modulus of annealed TiO2-Si NPl is about three times higher than for the pure Si NPl