<p>Designing multifunctional thermoelastic structures that simultaneously achieve load-bearing capacity and thermal insulation remains challenging, as mechanically strong materials typically exhibit high thermal conductivity, while effective thermal insulators often lack sufficient structural strength. To resolve this conflict, this study proposes a dual-scale topology optimization framework for structures integrating thermal insulation with load-bearing functionality. At the microscale, porous unit cells with low effective thermal conductivity are optimized to replace solid materials in the support structure, thereby reducing thermal shorting. At the macroscale, structural configurations are optimized, and the material savings from the microscale are reallocated to enhance global stiffness. Three optimization cases are presented. The first two illustrate how the framework captures topological features of transient heat conduction and thermoelastic structures under varying thermal durations and different thermal–mechanical objective weightings. The third case focuses on the integrated design, demonstrating the effectiveness of the dual-scale strategy. Comparative analysis shows that this approach yields up to 50% improvement in both thermal insulation and structural stiffness over mono-scale optimization. The results are further supported by numerical simulations, confirming the advantages of the proposed framework.</p>