This study investigates the flexural capacity of prefabricated truss-beam slabs as a cost-effective and time-saving alternative for conventionally constructing lighterweight reinforced concrete slabs. The conventional methods of casting and curing slabs are time-consuming and costly. Therefore, the development of innovative slab types and construction techniques is a necessity. The prefabricated truss-beam slabs consist of precast truss beams with lightweight blocks, such as Expanded Polystyrene Sheet (EPS) blocks, placed between them. Using EPS blocks significantly reduces the weight, thereby reducing the size of structural elements and the amount of reinforcing steel bars. The system requires less formwork and stringer support. Furthermore, installing precast beams on-site saves construction time and reduces costs. The study investigates the effects of different parameters on the flexural performance of the prefabricated truss-beam slabs. This includesthe impact of stirrup configuration, reinforcement ratio, and span. The results indicate that all the prefabricated beams exhibit good flexural performance. It was found that the stirrup configuration has minimal impact on the flexural performance of the prefabricated truss-beam slabs. Longer spans resulted in increased deflection but decreased capacity. Higher reinforcement ratios led to reduced deflection and increased capacity. In addition, the cost analysis revealed that the prefabricated truss-beam system is more cost-effective than solid slabs and polystyrene-filled ribbed slabs. Overall, this research demonstrated the viability of prefabricated truss-beam slabs as a lighter-weight and cost-effective solution for efficient floor construction in reinforced concrete structures.