<p>High-performance and lightweight materials design is a pressing need in aerospace applications (e.g., aircraft ailerons, flaps, and rudders). However, the unique functionality requirements in strength, weight, and resistance to environmental factors, such as temperature fluctuations and corrosion, challenge traditional structure design methods such as topology optimization. While sandwich panel composites with lattice cores are widely used in aerospace components and modern additive manufacturing techniques open new possibilities for sandwich core structure design with requirement functionalities, the delicate design brings computational challenges for both optimization and manufacturing. This paper presents an inverse design framework for sandwich structure optimization with implicitly represented architected cellular materials to address these issues. Specifically, cellular materials are implicitly represented (described by implicit functions) as building blocks in the core structure design. A multi-objective topology optimization problem is formulated to maximize the core structure’s mechanical and thermal performances. Lastly, the nature of function representation for ease-of-additive manufacturing computations is illustrated with a direct slicing algorithm without generating memory-expensive standard tessellation language (STL) files. The proposed design framework is validated in two practical aerospace design case studies, and experimental results demonstrate the effectiveness of the proposed optimization algorithm and STL-free scheme for additive manufacturing.</p>