Even though the 316L steel is widely utilized in manufacturing biomedical devices including hip joints, screw, plates, and nails, these devices are reported to fail at the early period of implantation caused by inferior biological responses, wear, corrosion, and fatigue. Coating the surface is therefore considered as the underlying factor to mitigate these occurrences. This research aims to evaluate the modified 316L surface through hydroxyapatite powder (HAp) mixed-electrical discharge process (EDM) for potential bio-implants. Moreover, this study focuses on the parametric effects on the modified surface responses. To synthesize a biocompatible and hard coating, HAp was added in the mineral oil. Several surface characterization methods including Profilometer, Goniometer, Scanning-electron microscope (SEM), powder X-ray diffraction (XRD), Energy dispersive X-Ray (EDX), Atomic force microscope (AFM), Vicker's hardness, and biocompatibility test were carried out in this study. The morphological analysis reveals a few micro-cracks formation with shallow craters and nanopores. The elemental analysis confirms Ca, O, P, C, and Ti presence on the machined surface, which replace Fe, Ni, and Cr. A uniform thin coating of 15.29 µm attributing biocompatible oxides, hydrophilicity, and nano-scale SR of 18.9 nm is obtained. Formation of the hard carbides improves surface microhardness by about 80. The modified specimen attribute s to a high biocompatibility due to the desired Ca-P based oxides formation. The proposed method can be used for processing 316L steel for a long-term success as the bio-implants. © 2021 Elsevier B.V.