The demand for agrostone in the building sector is undoubtedly being an issue of concern. This study aimed to replace the presently used glass fibers with alkali-treated false banana fiber (FBF) to reduce cost and further pressure on the environment. This study also investigates the effect of alkali treatment conditions on water absorption and tensile strength of the fiber at concentration of 3, 5.5, and 8 w/v%, at the temperature of 50, 70 and 90 oC and duration of 30, 45, and 60 minutes. The study also encompasses various aspects such as composition analysis, Fourier transform infrared, Spectroscopic analysis, thermogravimetric analysis, and scanning electron microscopic analysis of FBF. The study explores the effect of varying untreated and treated fiber content on matrix weight percentage ratios of 1.5/98.5, 2/98, 2.5/97.5, and 3/97 on the tensile strength, compressive strength, flexural strength, water absorption, and density of the fabricated agrostone; those properties were compared with glass fiber reinforced agrostone. The fire resistance, acid and alkali endurance of the agrostone panel were also tested at the maximum strength for both untreated and alkali treated fiber reinforced agrostone. The optimum FBF treatment conditions were identified using central composite design software, and the results showed that at 6.3%, 80.6oC, and 60 min, the fiber had improved properties. The enhanced values of tensile, compressive and flexural strength for alkali-treated reinforced agrostone are 27.69±0.48 MPa, 17.96±0.14 MPa, 25.78±0.61 MPa at fiber to matrix ratio of 2.5/97.5; while for untreated fiber reinforced agrostone the corresponding values are 21.07±0.57 MPa, 15.78±0.25 MPa, and 19.07±0.36 MPa respectively. The mechanical properties of alkali-treated FBF are comparable with glass fiber reinforced agrostone tensile strength of 28.4±0.81 MPa, compressive strength of 18.32±0.46 MPa, and flexural strength of 26.17±0.32 MPa and it improved the tensile strength to 31.4%, compressive strength to 13.8%, and flexural strength to 35.2%. At the point of maximum strength, the agrostone panels exhibited a water absorption rate of 15.04±0.56%, which indicates better resistance and durability, and a density of 1.54±0.017 g/cm2 indicating moderate density and good structural integrity for light-weight construction. The panels showed good resistance to harsh environments. Alkali treatment significantly improves fibers tensile strength and its adhesion to the matrix, leading to improved properties. Hence, it can be concluded that FBF can be used as a reinforcing material substituting glass fiber to produce good-quality agrostone with potential benefits in terms of sustainability and 14% cost reduction. Keywords: false banana fiber, agrostone, low cost building materials, composites, reinforcement