Abstract: Objective To address the issue of low strength in welded joints between aluminum alloy bodies and steel studs, a welding configuration featuring a stainless steel stud with internal and external double-threaded structures penetrating into an aluminum substrate was designed, and a shoulder-constrained stud friction welding method was proposed. Methods This study focuses on 7 series aluminum alloy plates and 304 stainless steel, fabricating stud welded joints under parameters of 1 200 r/min rotation speed, 7.5 mm feed rate, and 40 kN forging force. Results The results demonstrate that the obtained joints exhibit excellent surface formation and a tightly bonded interface. Under the constraint of auxiliary shoulder, the ram’s horn-shaped radial flash typically formed in conventional friction welding is transformed into filler material tightly bonded to stainless steel stud interface, while the extruded excess aluminum material forms a surface-sealing thickened ring beneficial to performance. The internal and external double-threaded structure of stainless steel stud significantly enhances flow capacity of the plasticized aluminum, resulting in fine equiaxed grains throughout aluminum structure within stainless steel stud cavity and its periphery. No significant defects were observed at the aluminum/steel interface, and a certain thickness of intermetallic compounds was present at the transition interface, achieving a mechanical-metallurgical hybrid joining. Tensile load-bearing capacity of welded joints reached 55 kN, representing a 72% improvement compared to previously reported tensile loads for studs of the same specifications. Conclusion This study provides a novel solution for high-quality joining between thick high-strength lightweight alloy plates and steel studs.