Display omitted •Super hardness and toughness of VSiN are achieved with Si content at 5.5 at.% Si.•With Si content, highly textured columnar grains, refined columnar grains, nanocomposite structure are formed.•DFT revealed that the ternary VSiN coatings become more ductile as the calculated Cauchy pressures (PC) raise, while the Pugh’s ratios (G/B) decrease.•Transfer of electrons to the Si-N bond from the neighboring V-N bonds causes Friedel oscillations and multiplication of the slip system. Microstructural evolution and deformation mechanisms of magnetron sputtered V-Si-N coatings with various Si contents are investigated by transmission electron microscopy, X-ray absorption spectroscopy, and ab initio calculations. A small amount of Si atoms was dissolved into the cubic VN lattice, locally reducing the neighboring V-N p-d hybridization near the Si site. The Si content was found to impact the architecture of coating significantly. With increasing Si content, the microstructure evolved through three different architectures: (i) highly textured columnar grains, (ii) refined columnar grains, and (iii) nanocomposite structures where elongated grains were bounded by vein-like boundaries. Enhanced damage tolerance was observed in the nanocomposite structure, where multiple toughening mechanisms become active. Ab initio calculations revealed that the incorporation of Si monolayer in the (111)-oriented VN resulted in the formation of weaker Si-N bonds compared to V-N bonds, which allowed a selective response to strain and shear deformations by assisting the activation of the slip systems.