<p>The increasing demand for bricks and cement in the construction industry has resulted in significant depletion of natural resources, particularly water and soil, leading to severe environmental degradation. While the dry-pressed and stiff mud process indeed uses less water, the dominant conventional practices in India and many developing countries still involve the soft mud process, which requires large quantities of water. Hence, conventional brick manufacturing is highly resource-intensive, relying heavily on soil extraction and a large volume of water, thereby raising sustainability concerns. In response, this study introduces a novel approach by repurposing two underutilised industry byproducts, waste foundry sand (WFS) and polymeric thermoplastic waste (PTW), which consists of mixed post-consumer plastic, including Polyethene terephthalate (PET), High-density polyethene (HDPE), Low-density polyethene (LDPE), Polypropylene (PP), and multilayer plastic (MLP) as disposed plastic waste. To develop a high-performance composite brick. This approach is distinctive in combining WFS with thermoplastic waste, optimising material proportions, and utilising advanced manufacturing techniques to reduce dependency on virgin raw materials. Composite bricks resulted in a specific gravity of 2.48 and a finess modulus of 2.133. The developed brick achieved a water absorption of 0.69 for poly sand brick (PSB) and 0.92 for perforated leg brick, and an impressive compressive strength of 4.98&#xa0;N/mm². These results demonstrate that PTW-WFS composite bricks offer a balance of adequate strength and reduced water absorption, providing a cost-effective and eco-friendly solution for construction applications. This composite brick not only addresses pressing environmental challenges but also aligns with several United Nations Sustainable Development Goals (SDGs), thus contributing to sustainable construction without compromising the structural integrity of performance.</p>