This article focuses on the investigation of properties of Phoenix sp . fiber based geopolymer composites. Control samples (0 wt.%) and fiber reinforced samples (1, 2, 3, and 4 wt.%) with different quantities were produced and determined their physical, mechanical, morphological, ultrasonic pulse velocity, water absorption, thermal conductivity and fracture toughness properties. The outcomes show that the incorporation of Phoenix sp . fibers to geopolymer improved the splitting tensile (1.28–2.35 MPa), compressive (27.85–32.18 MPa) and flexural strengths (3.34–6.53 MPa). By contrast, as the fiber loading increased to 4 wt.%, the workability and bulk density of geopolymer decreased to 86% and 13%, respectively. Furthermore, a linear relationship was evidenced between the bulk density and thermal conductivity, as well as ultrasonic pulse velocity and compressive strength. Due to the hydrophilic character of Phoenix sp . fibers, the water absorption increased as the fiber content increases. Due to the local mechanisms that control the bridging activity, the addition of Phoenix sp . fibers improved the fracture toughness of the composites.