This study investigates the effects of using wheat straw ash (WSA) as a cementitious material and coir fiber as reinforcement on the mechanical properties, permeability, and embodied carbon of concrete. A total of 255 concrete samples were prepared with a 1:1.5:3 mix proportion and a water-cement ratio of 0.52, and all specimens were cured for 28 days. The results showed that adding 10% WSA and 2% coir fiber increased the compressive, splitting tensile, and flexural strengths to 33 MPa, 3.55 MPa, and 5.16 MPa, respectively, compared to the control mix. The permeability of concrete incorporating 4% coir fiber and 20% WSA was reduced by 63.40% compared to the control mix, which can prevent the propagation of cracks. Additionally, the embodied carbon of concrete decreased with increasing levels of WSA and coir fiber. The study recommends using 10% WSA and 2% coir fiber for optimal results. The findings contribute to the development of environmentally friendly and sustainable construction materials.This study investigates the effects of using wheat straw ash (WSA) as a cementitious material and coir fiber as reinforcement on the mechanical properties, permeability, and embodied carbon of concrete. A total of 255 concrete samples were prepared with a 1:1.5:3 mix proportion and a water-cement ratio of 0.52, and all specimens were cured for 28 days. The results showed that adding 10% WSA and 2% coir fiber increased the compressive, splitting tensile, and flexural strengths to 33 MPa, 3.55 MPa, and 5.16 MPa, respectively, compared to the control mix. The permeability of concrete incorporating 4% coir fiber and 20% WSA was reduced by 63.40% compared to the control mix, which can prevent the propagation of cracks. Additionally, the embodied carbon of concrete decreased with increasing levels of WSA and coir fiber. The study recommends using 10% WSA and 2% coir fiber for optimal results. The findings contribute to the development of environmentally friendly and sustainable construction materials.