The current study investigates the effect of dune sand (DS) and fly ash (FA) on the microstructure of fiber-reinforced concrete (FRC). Concrete is a widely used construction material, and understanding its behavior under different conditions is important for optimizing its performance. The use of alternative materials, like FA and DS, in concrete production has gained attention due to their abundance and potential environmental benefits. The research methodology involved the preparation of FRC mixes with different combinations of FA and DS, along with varying fiber content. The microstructural analysis of the samples was conducted through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The findings revealed that the addition of FA and DS influenced the microstructure of the FRC. Furthermore, the inclusion of FA contributed to improved pore structure and enhanced the pozzolanic reaction, resulting in a denser microstructure. The incorporation of steel and basalt fibers demonstrated significant effects on the microstructure of the concrete. The results provide valuable insights for optimizing the design and performance of concrete structures in arid regions while considering sustainable materials.