The study significantly contributes to the knowledge of utilizing blast furnace slag as a reinforcement material in Al-4Mg alloys, highlighting its potential for various applications in the automotive, aerospace, and automotive industries. By successfully fabricating composites with varying weight percentages of slag. The thorough investigation of grain structure changes and uniform particle distribution through advanced microscopy techniques provides valuable insights into the reinforcement mechanisms. The observed improvements in mechanical properties, particularly in hardness, density, Young's modulus, compressive strength, and tensile strength, with the addition of 5% slag reinforcement, underscore the practical significance of these composites. This finding indicates that Al-4Mg alloy composites with blast furnace slag can potentially offer lightweight yet high-strength materials suitable for demanding applications in the automotive and aerospace industries. Overall, the study's results not only demonstrate the enhanced performance of the composites but also highlight the eco-friendliness and cost-effectiveness of using blast furnace slag as a reinforcement material.