This experimental study investigates the feasibility of utilising coconut shell as a partial replacement for conventional coarse aggregates in M20 grade concrete. The aim is to evaluate the mechanical and physical properties of lightweight concrete produced using varying percentages of coconut shell aggregates (0%, 10%, 20%, and 30%). Experimental parameters such as workability, density, and compressive strength at 7, 14, and 28 days were analysed. Results indicated that a 20% replacement of coarse aggregates with coconut shells provided an optimal balance between strength and weight reduction, making it suitable for non-structural and low-load-bearing applications. The study concludes that coconut shell concrete is an eco-friendly alternative for sustainable construction practices.