This study explores the integration of Topology Optimization (TO) with non-planar 3D concrete printing (NP-3DCP) to address environmental and material efficiency challenges in construction. We present a novel approach leveraging robotic NP-3DCP for creating lightweight, structurally optimized architectural components, specifically focusing on load-bearing walls. The advantages of this approach were demonstrated through the manufacturing of two prototypes, Shell Wall and Branch Wall, showcasing significant material savings and reduced carbon footprint without compromising structural integrity. Our methodology encompasses the generation of a non-planar printpath, material extrusion control for variable layer height, and the integration of rebar and thermal insulation within the casting process. The results showcase the potential of this approach in producing complex geometries with improved environmental performance, suggesting a promising direction for the future of sustainable concrete construction.