The search of finding best vegetable oil based nanofluid from a set of three nanoparticle enriched cutting fluids for machining is core objective of the work. Extensive research has been done to replace conventional cutting fluids by nanofluids, but abundant analysis for vegetable oil based nanofluids is accomplished in this work which was not seen earlier. Also, the study investigated the cutting performance and comparative assessment towards machinability improvement during hard turning of high-strength-low-alloy (HSLA) AISI 4340 steel using four different compositions of nanofluids by minimum quantity lubrication (MQL) technique. Cutting are investigated and analyzed through this article during hard turning using minimum quantity lubrication (MQL). Cutting force, tool wear (flank and crater), surface integrity (surface roughness, residual stress, microhardness, and surface morphology), and chip morphology are considered as technological performance characteristics to evaluate the machinability of hardened AISI 4340 steel. Additionally, the effect of various fluid properties like thermal conductivity, viscosity, surface tension and contact angle were examined for all nanofluids. Three set of nanofluid samples were prepared using Al2O3, CuO and Fe2O3 with rice bran oil and their various properties are analysed at 0.1% concentration. On comparison among these three nanofluids used, CuO nanofluid exhibited superior behavior followed by Fe2O3 nanofluids while Al2O3 nanofluid was last in the row.