The voltage and current signals and arc images during arc ignition of tungsten inert gas - metal inert gas (TIG-MIG) hybrid welding were recorded using a data acquisition system and a high-speed camera. The data was used to study the effects of electrode polarity of the TIG welding and the MIG welding and the shielding gas type for the MIG welding on the arc ignition of TIG arc-assisted MIG welding. MIG welding with direct current electrode positive is necessary for TIG arc-assisted MIG welding to achieve non-contact arc ignition through an elongated discharge channel. TIG welding with direct current electrode negative or positive only affects the ease of non-contact arc ignition for TIG arc-assisted MIG welding. MIG welding achieves non-contact arc ignition because the electrons in the outer layer of the TIG arc move towards the end of the MIG welding wire where they collide with neutral particles in the surrounding shielding gas which ionizes some of them and generates many positively and negatively charged particles. The gap conductivity then significantly increases and the gap breaks down at low voltage. MIG welding with pure Ar shielding gas more easily achieves non-contact arc ignition than with Ar + 1% O₂ (volume fraction) or Ar + 15% CO₂ (volume fraction).