<p>Coconut fiber is a natural material with high potential to replace expanded polystyrene (EPS) due to its biodegradability, mechanical strength and large-scale availability. This paper reviews its properties, treatments and applications, highlighting its reduced environmental impact compared to synthetic materials. Treatments applied to coconut fiber include physical and chemical methods to improve its stability and functionality. These include alkaline treatment, silanization, the use of liquid smoke and ultrasound modification, techniques that optimize its thermal, mechanical and hydrophobic resistance. Recent research explores the use of organic acids for sustainable fiber modification. Despite its advantages, its implementation faces challenges such as compositional variability, moisture absorption and the need for industrial processing. However, the growing demand for sustainable materials and the abundant availability of coconut fiber open opportunities in biodegradable packaging, construction and biocomposites with advances in processing and development of new treatments; coconut fiber emerges as a viable and ecological alternative to EPS and other conventional polymers.</p>