The natural fiber–reinforced polymer composites gaining substantial importance in recent years due to their unique properties compared to synthetic composites. In India (especially northeastern part), cultivars and industries mostly focus on pineapple fruits, leaving leaf to mainly compost or burn and decay as an agro waste. In this article, pineapple leaf–based (variety type Kew or Giant Kew from Silchar, Assam, India) short fiber–reinforced polymer composites as a function of fiber composition and composite thickness on mechanical properties are analyzed. In this regard, short pineapple leaf fibers (≈ 1 mm to 2 mm) as reinforcement + epoxy resin (Lapox (L12) resin + K6 hardener) as matrix material are used for composites. Subsequently, six different fiber compositions (as 0, 1, 5, 10, 15, and 20 wt%) with composite specimen’s thickness (as 3 and 5 mm) are prepaid. Later, mechanical properties like tensile strength, flexural strength, and toughness and hardness values for each of the composite specimens are evaluated. The result shows that the addition of short fiber can improve the mechanical properties and found in all the cases composites with 10% of reinforcement + at 5-mm thickness show better performance than the other combinations.