<p>The thermal conductivity of energetic materials significantly affects their safety and environmental adaptability. To enhance the thermal conductivity of polymer-bonded explosives (PBXs), this study used melamine particles (MP) as PBX substitutes, with graphene nanosheets (GNPs) as thermal fillers and fluorinated polymer (F2314) as the binder. The MP@GNPs core–shell structure was initially constructed using the electrostatic self-assembly method. Subsequently, the MP@GNPs/F2314 core–shell structure was fabricated via the water suspension method, and a three-dimensional thermally conductive network was established through hot pressing. At 0.5 wt% GNPs, the composite’s thermal conductivity (<i>k</i>) increased by 79% compared to pure MP. Further validation using HMX-based PBXs showed a 47% improvement (0.5367 W·m⁻¹·K⁻¹). The temperature gradient and distribution of thermal stress in PBX cylinders under complex thermal variation were evaluated using finite element analysis.</p> Graphical abstract <p></p>