Abstract This study investigates the mechanical and machinability properties of the aluminum 6061 reinforced with boron carbide (B4C). Four aluminum 6061 composite specimens reinforced with 5 wt%, 10 wt%, 15 wt%, and 20 wt% B4C were fabricated using a powder metallurgy and hot-extrusion method. The composite samples were investigated to elucidate the influence of different weight fractions of B4C reinforcement content on the hardness, fracture toughness, tensile strength, transverse rupture strength (TRS) and milling properties of the resulting composites. The milling tests were performed based on the Taguchi mixed-orthogonal-array for experiments, L16 (44 × 21), to determine the effect of B4C content on surface quality and energy consumption for different cutting parameters under dry- and compressed-air cooling and using an uncoated carbide insert. The results reveal that the B4C particles are uniformly distributed in the matrix and that the fracture toughness decreases and the hardness increases as the weight fraction of the reinforcement increases. The highest tensile and transverse rupture strength are for Al6061/5 wt% B4C and Al6061 reinforced with 10 wt% B4C composite material has the best fracture toughness from among the specimens measured. At higher milling speed and lower cutting feed and under dry machining conditions, an excellent surface quality is obtained after milling all composites materials and the surface finish improves with increasing B4C content in the matrix. The power consumption and surface roughness increases when cooling with compressed air.