Adhesively bonded skin-to-stiffener joints are critical structural components in structural applications, particularly aerospace structures, providing significant weight savings, load transfer efficiency, and damage tolerance. This review includes an integrated examination of stiffener types, adherend materials, manufacturing techniques, bonding process, surface treatment, adhesive material, adhesive filler, mechanical testing, and environmental conditions connected with these joints. Overall, joint performance is most strongly governed by the selection of the bonding process, surface treatment, adhesive material, adhesive filler, and environmental exposure. In terms of the bonding process, co-curing is often the most effective bonding procedure, while co-bonding and secondary bonding are still useful for repair or complex constructions. Surface treatment, including sanding, grit blasting, peel ply, laser ablation, and anodizing, is crucial to guaranteeing bond quality and long-term durability. Aerospace applications rely heavily on high-performance epoxy-based structural adhesive due to its superior strength, toughness, and environmental resistance. Adhesive fillers, such as nanofiber interleaved and CNFs, considerably increase the structural performance of the skin-stiffener joint. Environmental conditions, in particular, elevated temperatures, subzero temperatures, humidity, and hygrothermal aging, significantly affect joint strength and failure behavior. The review identifies important research gaps in surface pre-treatment, new filler material, and long-term aging effects at environmental conditions, and provides recommendations for advancing the next generation of adhesively bonded stiffened structures. © 2026