This study investigated the physical and mechanical properties of hybrid composites from natural rubber (NR)/high density polyethylene (HDPE)/Mengkuang fiber (MK)/eggshell powder (KT). Preparation of hybrid composites, NR/HDPE/(MK/KT) was produced using composition 40/60/(20) with filler material, MK/KT was varied at 0/20, 5/15, 10/10, 15/5 and 20/0. Preparation of hybrid composites is produced using melt blending method in internal mixer at 135oC and mixing rate at 50 rpm for 18 minutes. The resulting samples were tested in terms of strain testing, impact test and water absorption test, while the structure and morphology were characterized using Fourier Infrared Transformer (FTIR) spectroscopy and scanning electron microscopy (SEM). In this study, the hybrid composite with MK/KT 5/15 filler provides optimum yield with maximum stress strength of 7.84 MPa and maximum impact strength of 6.60 kJ/m2. In addition, the treatment of MK fibers covers pre-treatment with sodium hydroxide (NaOH) solution, and immersion with hexadecyltrimethoxysilane (HDS) solution has been performed to enhance the physical and mechanical properties. The composition of the filler with the highest percentage of mengkuang fiber with 20% showed an increase in water absorption rate. Overall, the addition of egg shells has been shown to enhance the physical and mechanical properties of resulting composite.