The presented process combination couples a laser beam and two MIG welding torches in one setup for one side welding of thick metal sheets. Using this welding process combination of a disc laser with a maximum output power of 16 kW and two high power MIG sub-processes for joining high material thicknesses, the welding speed can be significantly increased in comparison to conventional joining methods. In order to benefit from these economic advantages and to make brilliant high power lasers for industrial applications useful, this process combination needs to run robustly for conventional welding practices as well as for common gap and tolerance ranges. For the process development, plates of the aluminum alloy EN AW-6082-T6 with a thickness of 12 mm were joined in a flat position with a single process step over the whole thickness. The developed weld seams reach the quality level B of ISO 13919-2:2001 and of ISO/FDIS 12932:2012. The process development consists of a variation of different parameter such as the welding speed, the wire feed rate, or the process distance between the laser beam and the first MIG torch. To confirm the multifaceted applicability and the robustness of this welding process combination, the process limitations were determined with regard to gap bridgeability and vertical edge offset.