Aluminium 6061 (Al6061) alloy, which is known as commercial alloy, is massively used in aviation and automobile industries. Therefore, research on Al6061 alloy is gaining significance among scientists and researchers all over the world as it provides light weight, high strength and stiffness, high impact, and corrosion resistance in engineering applications. The comprehensive analysis of mechanical behavior under large stress-strain deformation responses of the alloy is studied over a wide range of strain-rates such as 1 × 10−3 s−1, 1 × 103 s−1, 2 × 103 s−1, and 3 × 103 s−1 under room temperature to elevated temperatures of 100°C and 200°C. In this regard, this study aims to evaluate the Johnson–Cook strength and fracture constants utilizing the Johnson–Cook constitutive model equations. Furthermore, the evaluated constant parameters have been used to perform numerical simulation analysis utilizing ABAQUS/CAE software. According to the study’s findings, the critical perforation velocity was found to be 70 ms−1 when a flat-nosed bullet (45 mm length and 12 mm diameter) made of stainless steel weighing 50 grams was fired normally to the center of a square plate specimen of Al6061 alloy. The specimen of the square flat plate was prepared with side 205 mm and 2 mm thickness (205 × 205 × 2 mm3). A good correlation for critical perforation velocity of experimental acquisition data and numerical simulation results has been found. These findings increase the knowledge of the material’s response application to the high-velocity impact that can be used in arms-ammunition, aviation, marine, automobile, and home appliances.