Metal inert gas (MIG) welding provides advantages such as a high deposition rate, high thermal efficiency, and suitability for automated and efficient production. Due to their high specific strength and good damping performance, magnesium alloys have broad application prospects in transportation, aerospace, and other industries. MIG welding is considered a suitable joining method for magnesium alloys, and significant research efforts and technological developments have been devoted to this field. This paper presents the current research status of MIG welding of magnesium alloys, reviews related studies on droplet transfer modes, microstructure evolution, and MIG hybrid welding technologies, and discusses future research directions for MIG welding of magnesium alloys.