With the development of the steel industry, the annual production of industrial slag has been steadily increasing. Millions of tons of steel slag waste have become an economic burden for the steel sector. The disposal of inefficient steel slag waste has also caused severe air and water pollution. As the manufacturing of various products, construction projects, transportation, and industrial machinery are all closely tied to the steel industry, a significant amount of by-products—namely ground granulated blast furnace slag (GGBS) and reduction slag—are generated annually, totaling approximately 400,000 to 1.6 million tons. In contrast, traditional bricks used in construction around the world are commonly made by extracting natural clay minerals and subjecting them to high-temperature firing processes that consume large amounts of energy. This study proposes an alternative approach by mixing GGBS with reduction slag to produce environmentally friendly green energy bricks. The results show that incorporating 25% reduction slag is optimal, as it minimizes shrinkage during high-temperature sintering. The resulting bricks also exhibit compressive strengths ranging from 11 to 20 MPa, which meets the requirements for general infrastructure applications. Moreover, the eco-bricks developed in this study emit only about one-third of the carbon emissions compared to traditional fired bricks. This approach not only helps conserve natural resources but also promotes the beneficial reuse of industrial by-products. In tropical countries, these eco-bricks can be applied to sidewalk tiles, curbstones, interlocking bricks, grass pavers, or indoor partition walls, and they also offer significant potential for improving indoor temperature regulation.