Natural fibers are used in the composite as a more recent development, both as reinforcement and filler in the polymer matrix. The advantages of using natural materials are their low cost, high strength, plentiful availability in nature, and ease of extraction. Certain synthetic materials, when heated, release harmful substances. Therefore, switching to natural materials is better for the environment. The characterization of Fishtail Palm (Caryota mitis) Leaf Stalk Fiber (FPLSFs) was explored experimentally in this research effort. This study describes the physical–chemical characterization of Fishtail Palm (Caryota mitis) Leaf Stalk Fibers (FPLSFs). Thermogravimetric examination (TGA), Single-Fiber Tensile Test, Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), SEM examination, and Thermo Gravimetric Analysis. Fishtail Palm Leaf Stalk Fiber (FPLSFs) was discovered to have greater cellulose content of 63.67 weight percent, density of 1473 kg/m3, diameter of 380.85 m, Crystallinity Index of (CI) 31.37%, tensile strength of 249.23 MPa, and thermal stability of 326 °C. These fibers’ general characteristics suggested that they might be a different source of reinforcement material for the creation of composite materials.