<p>Fused deposition modeling (FDM)-based metal additive manufacturing offers a practical route for producing geometrically customizable metallic electrodes; however, post-processing and surface modification are critical for obtaining suitable electrochemical performance. In this study, 17-4PH stainless-steel electrodes were fabricated using a metal-polymer composite filament, followed by debinding and graphite-assisted sintering to reduce surface oxidation and preserve electrical functionality. Ni-based coatings were subsequently electrodeposited from an Ethaline-based deep eutectic solvent containing Ni²⁺ under applied potentials of −1, −1.5, and −2&#xa0;V. The effects of electrodeposition potential on surface morphology, elemental composition, phase structure, surface bonding, and electrochemical performance were investigated using SEM/EDS, XRD, FTIR, chronoamperometry, cyclic voltammetry, galvanostatic charge–discharge, cycling stability, and electrochemical impedance spectroscopy. SEM and EDS analyses confirmed the formation of a Ni-enriched surface layer after electrodeposition. Electrochemical results showed that the electrode deposited at −2&#xa0;V exhibited the highest areal capacitance of 517&#xa0;mF&#xa0;cm.⁻² at 10&#xa0;mV&#xa0;s⁻¹. GCD and EIS analyses further supported the improved charge-storage behavior and lower interfacial impedance of the −2&#xa0;V electrode. These findings demonstrate that combining graphite-assisted sintering with Ni electrodeposition is an effective post-processing and surface modification strategy for improving the electrochemical performance of FDM-printed stainless-steel electrodes for supercapacitor applications.</p>