Hybrid welding has been introduced as a process that combines one laser and one arc welding process to work together. These advanced joining processes are effective and outweigh several drawbacks of mere single methods. Hot spots, made by laser to the joint, have been reported to stabilise the arc and change the way of material transfer in the arc. The arc is also attracted and constricted by the hot spot. This phenomenon has been utilised in this study in order to get the process adaptable inside very narrow grooves. This novel approach, combined with multipass techniques, enables a considerable increase in the thickness of the parts to be welded. Welding continues to employ rather low total heat input levels and, consequently, results in very low thermal distortions in joining thick sections. As the process retains a keyhole typical of high energy density welding, the process is also very effective for joining thick sections. Based on the above argument, the process further developed in this study should be considered when evaluating welding processes for joining vacuum vessel sectors of ITER. The same certainly applies to many other demanding thick sections and hence heavy high precision components.