We designed nine distinct compositions of AlCrNbSiTi high-entropy alloy targets by adjusting the Al, Cr, Nb, and Ti contents, while maintaining the Si content at 7.7 at.%. We fabricated (AlCrNbSiTi)N films using the high-power impulse magnetron sputtering (HiPIMS) technique. By analyzing the microstructure and properties of the films, we have identified an expanded compositional window. This expansion enables (AlCrNbSiTi)N films with varying composition ratios to consistently demonstrate excellent mechanical properties. This consistency proves advantageous in terms of both sputtering target preparation and coating applications. In this study, all films had a single face-centered cubic (NaCl-type) structure with a crystallite size of ∼6 nm and lattice constant of ∼4.22 Å. The hardness of the films varied between 25.9 and 27.6 GPa. The thickness of the oxide layer formed when the films were annealed at 800 °C for 2 h under atmospheric conditions was approximately 30 nm, regardless of the composition. We also examined the cutting properties of (AlCrNbSiTi)N coatings on carbide cutting tools. Under dry milling conditions and extended cutting distances, the (AlCrNbSiTi)N coatings exhibited a remarkable reduction in flank wear length, with reductions of 78%, 64%, and 68% when compared to the commercial coatings TiN, TiAlN, and AlTiN, respectively. Furthermore, these coatings remained intact without peeling during milling on a 304 stainless steel workpiece. This research demonstrates that the combination of HiPIMS and high-entropy (AlCrNbSiTi)N could provide hard coatings with excellent performance during cutting. The characteristics of the coatings are attributable to the fineness and high density of the films deposited by HiPIMS and the synergistic lattice distortion and cocktail effects, which are similar in the compositional window of the designed alloy system.