In this research work strips of a TRIP-type AHSS steel have been welded using Gas Metal Arc Welding (GMAW) and CO2 Laser Beam Welding (CO2-LBW) processes and the resultant mechanical properties of the welded joints have been measured by means of hardness and tension tests. It has been found that CO2-LBW leads to a relatively high hardness in the fusion zone (FZ), indicating that the resultant microstructure is predominantly martensite. In the heat-affected zone (HAZ), a mixture of phases consisting of bainite and ferrite is present. Similar mixtures of phases have been found in the HAZ and FZ of the GMAW samples. Although the presence of these similar mixtures of phases, the results obtained by tension tests have shown a different behavior in GMAW and CO2-LBW specimens. In fact, no mechanical degradation in HAZ and FZ has been observed in GMAW samples, as all the fractures occurred in the base metal (BM). In contrast, the region adjacent to the HAZ of most samples welded using CO2-LBW failed by brittle cleavage. Probably, tempering effects in this region have promoted carbide growth and a relatively coarse microstructure, no embrittlement have been found that could be associated to the development of martensite.