The consolidation of polylactic acid/graphene nanocomposite via a novel SPS powder metallurgy route was elaborated in this study. The nanocomposite powders were prepared using the three-dimensional (3-D) tubular mixer and consolidated under different parameters of spark plasma sintering (SPS). The densification, porosity, hardness, and crystalline properties of the consolidated specimen were investigated as a measure of its mechanical strength. These properties were observed to have an obvious dependence on the sintering process parameters. The fracture morphology of the sample reveals the ductile fractured at elevated sintering temperature of 160 °C while a fragile intergranular fracture type was revealed at a lower sintering temperature of 135 °C. SEM images revealed a well-distributed and dispersed GNP in the PLA matrix across the varied process parameters of temperature and pressure. The crystallinity of the nanocomposite peak was enhanced via the process engineering of SPS. This was observed with increased crystalline peaks on the XRD and percentage crystallinity reported on the DSC. Changes in the range of transmittance with respect to sintering parameters were observed on the FTIR. The thermal stability improves with respect to the sintering temperature and pressure within the range of the parameters reported. This reveals a better mass barrier effect of the nanocomposite due to better intermolecular diffusion and reduced pore spaces in the sintered samples. The thermal stability was observed to appreciate due to the better polymer nanoparticle interaction. Hence, this study further attests that aside from the use of nucleation agents such as GNP and plasticisation, process engineering of SPS could help in modifying desired properties of nanocomposite.