CO2-laser welding of 12Kh18N10T stainless steel and a VT1-0 titanium alloy with the use of a composite insert obtained by means of explosive welding of four sheets (VT1-0 titanium, high-purity tantalum, M1 copper, and 12Kh18N10T steel) is experimentally studied. After mechanical processing, the insert is placed between the welded steel and titanium sheets. Butt-end welding of the steel and titanium sheets with the steel and titanium sides of the insert, respectively, is performed by a laser beam. Metallographic and spectrographic investigations are performed; mechanical properties of the resultant composite are tested. After thermal processing, the composite is found to break over the copper layer, which has a strength of 417 MPa.