This paper presents the results of experimental investigation on the machinability characteristics in conventional turning process of two different Al-Si alloy-based metal matrix nanocomposites (MMNCs), containing 0.5 vol.-% of Al2O3 nanoparticles and 0.5 vol.-% multi-wall carbon nanotubes (MWCNTs). The MMNCs were fabricated using stir casting technique. The influence of the nanofiller type as well as the turning machining parameters, typically, the cutting speed, feed rate and the rake angle of the cutting tool on the machinability characteristics, typically, the surface roughness, roundness error and material removal rate (MRR) were studied. The results revealed that cutting speed has the most significant effect on the roundness error and MRR of the nanocomposites. While, the rank angle is the most influential factor that affect the surface roughness of the nanocomposites.