Currently, one of the most challenging tasks for the scientific community is to identify a novel material that can replace petrochemical products. It is needed for the identification of novel natural fibers that can be used in polymer composites, enabling a better combination of polymers and fiber for a wide range of applications. In this regard, experimental investigations were conducted on Butea monosperma fiber (BMF) to understand its chemical, physical, and thermal properties. The chemical composition of BMF showed a significant cellulose (63.49%), lignin (17.58%), hemicellulose (18.16%), moisture (8.85%), and pectin (4.87%) content and minimum amounts of wax (0.26%) and ash (3.79%). X-ray diffraction XRD analysis showed that the BMF has a good crystallinity index of 79.993% and a crystallite size of 7.40 nm. The surface morphology, roughness, and elemental composition of the BMF were measured using scanning electron microscopy, atomic force microscopy, and energy-dispersive spectroscopy. Thermal properties of BMF were measured by thermogravimetric analysis and differential scanning calorimetry. The results showed thermal stability up to 296.14°C and a degradation temperature of 365°C, which makes it suitable for polymer composite fabrication. The chemical functional groups present in the BMF were identified using Fourier transform infrared analysis. The density of the BMF was 370 kg/m3, which was lower than that of existing fibers and showed good tensile properties. Compared with other recent scientific studies, the results showed that BM is best fit for reinforcement in natural fiber polymer composite materials and biocomposites.