<p>Natural fiber reinforced epoxy composites are increasingly investigated for sustainable engineering applications; however, their sensitivity to moisture absorption remains a major problem. This research investigates the impact of fiber surface modification and Syzygium Cumini filler addition on the water absorption behaviour of Murraya Koenigii reinforced epoxy composites. Novel hybrid composites were meticulously formed via the hand lay-up method with Syzygium Cumini filler contents of 0, 1, 2, 4, and 6 wt%. The composites are developed with and without chemical treatment of Murraya Koenigii fiber mats, where fiber treatment was conducted utilizing a 5% NaOH solution prepared in distilled water. Water absorption experiments were performed by submerging specimens in distilled water for 21 days. The results indicate that alkali treatment significantly reduces moisture absorption, and the treated fiber composite with 4 wt% Syzygium Cumini filler exhibited the lowest water absorption. These high-performance, eco-friendly composites can be used as automotive and construction panels, as well as in moisture resistant structural applications.</p>