Double glow plasma surface alloying was utilized to synthesize a nickel coating with controlled columnar crystalline architecture. The deposition process was systematically regulated with a fixed source electrode bias of −990 V and precisely controlled deposition temperatures (750, 800, and 850 °C) through cathode bias modulation. Plasma characteristics were quantitatively analyzed through argon emission spectroscopy, enabling precise determination of electron density and temperature. Elemental interdiffusion behavior was comprehensively characterized using electron probe microanalysis, revealing significant interface-pinning effects achieved through strategic manipulation of layer-by-layer and island growth mechanisms. Critical analysis of diffusion coefficients demonstrated comparable magnitudes between the primary diffusion coefficients, along with their cross-diffusion coefficient, suggesting substantial involvement of Inconel718 re-sputtering phenomena in the diffusion dynamics. The coating exhibited exceptional adhesion performance, maintaining structural integrity through 200 rigorous thermal cycling tests without observable delamination.