This paper intends to establish the possibility on the application of a hybrid (CO2 laser+GMA) welding process to austenite stainless steel (STS304L) by clarifying the bead profiles and mechanical characteristics of the hybrid welded joints. Moreover, the residual stress, plastic strain characteristics and their production mechanism of the welded joints were examined by thermal elastic-plastic analysis. The visual test of the welds was classified as quite stringent (Quality B′) in quality for weld imperfections in terms of four items (reinforcement, backbead, undercut and bead uniformity of the weld). The tensile strength of the hybrid welded joints was approximately 546 MPa, which satisfied the classification requirements. The hardness of the hybrid welded joints was within the acceptable range (the maximum value 340–360 HV).