<p>Previous research has validated the remarkable efficacy of the KTIG-MIG hybrid arc in enhancing MIG arc stability. In this study, a systematic investigation is conducted on the influence of KTIG current on the KTIG-MIG hybrid arc welding process. By varying KTIG current within 100–500 A, it is compared and found that the magnitude of KTIG current affects the arc deflection shape, droplet transfer behavior, current–voltage characteristics, weld formation, and the difference of microstructure and microhardness in the hybrid arc welding. The results are as follows at the given MIG current of 270 A with the increase of KTIG current: (1) The stiffness of the KTIG arc increases, and the reverse tilt angle of the MIG arc increases from 24.9° to 39.6°. (2) The droplet transfer mode changes from metal flow transfer at 100–200 A to spray transfer at 300–400 A; the current–voltage signals are more stable, and weld formation is smoother. However, at 500 A, excessive current pushes droplets away from the tungsten tip, the stability of electrical signals slightly decreases, and the weld formation is deteriorated. (3) The weld penetration exhibits an overall increasing trend except at 300 A. (4) As the proeutectoid ferrite increases while the fine acicular ferrite decreases, the weld melt zone hardness decreases from 220 HV_0.3 ~ 230 HV_0.3 to 190 HV_0.3 ~ 215 HV_0.3. These findings not only deepen the fundamental understanding of KTIG-MIG hybrid welding but also lay a robust foundation for the rational design of optimized welding parameters, thereby facilitating the broader industrial adoption of this advanced welding technology.</p>