In hard turning, the chip removal process is very difficult. One of the preferred auxiliary methods to reduce cost and improve quality is the use of cutting fluid. However, the use of conventional cutting oil has several disadvantages, such as polluting the environment, damaging employee health, and increasing production costs. Therefore, alternative methods are very important. In this study, nanoadditive-based cutting fluid and cryogenic cooling by liquid nitrogen, are compared in terms of machining performance in hard turning processes. Hardened AISI 420 was selected as the experiment material. 0.5 vol% graphene nanoplatelet (GnP) was added to the cutting oil to obtain nanofluid. The experiment variables were listed as three cutting speeds, three feed rates and two cooling conditions. Tool-chip interface temperature, surface roughness/topography, tool life, tool wear characterization and chip morphology were used to evaluate the experimental results. The results showed that cryogenic cooling was better in tool-chip interface temperature, tool life, tool wear and chip morphology, whereas nanofluid was better in average surface roughness and surface topography.