<p>The commercialisation of flexible lithium-sulfur batteries suffers from several intrinsic issues, including the insulating nature of sulfur, the shuttle effect of lithium polysulfides (LiPSs), and sluggish redox kinetics processes. Herein, we developed a CoSe₂-modified bilayer carbon-structured sulfur host that integrates the functions of “confinement-adsorption-catalysis”. The inner carbon framework layer is composed of a three-dimensional conductive hybrid network formed by CoSe₂ nanoparticles integrated with interconnected carbon nanotubes, facilitating rapid electron/ion transport while alleviating sulfur volume expansion during cycling. The homogeneously distributed CoSe₂ particles function as robust chemisorption and electrocatalytic centers, effectively trapping LiPSs and promoting their rapid redox reactions. Meanwhile, the outer micronscale graphene nanoflower carbon layer provides robust physical confinement, preventing the outward diffusion of soluble LiPSs and thereby inhibiting shuttle effects. As a result, owing to this “confinement-adsorption-catalysis” synergistic effect, the CoSe₂/CNT@GF-S achieves a significant discharge capacity of 1086 mAh g⁻¹ at 2 C, and even under sulfur loadings of 5.1 and 8.1 mg cm⁻², the cathode maintains high average areal capacities at 0.1 C, achieving 5 mAh cm⁻ for 100 cycles and 7.9 mAh cm⁻² for 50 cycles, respectively. Thus, this rational bilayer carbon structural design is an effective strategy for fabricating cathodes for high-performance flexible lithium-sulfur batteries.</p>