This study aims to investigate the mechanical properties such as tensile, flexural, and impact strength of oil-treated bamboo fiber/polyester laminated composites using an experimental and numerical approach. The present work is motivated by the gaps identified in the literature for making a laminated form of bamboo fibers using polyester resin and oil-treated bamboo strips. The purpose of oil treatment is to soften the lignin part of bamboo fiber resulting in more flexible fiber strands. Due to the softness of the noncellulosic composition of fiber, each cellulosic element of the fiber tends to slide one another. The composite is manufactured using hand layup methods with a fiber/matrix ratio of 35%/65% by volume. The fiber orientations used in the laminates are [0]5 for tensile and bending tests, and [0]7, [0/±45/0̅] 𝑠 and [(0/90)3/0] for impact tests. The maximum tensile stress and flexural stress of oil-treated bamboo fiber reinforced polyester composite (OBFP) are 193.3MPa and 173.4MPa which is 39.6% and 50.1% respectively higher than untreated bamboo fiber reinforced polyester composite(UBFP). Due to the oil treatment effect of fiber, their tensile and flexural strain also increases by 25.06% and 25.7% respectively. Compared to tensile strength improvement, the flexural strength is more improved due to oil lubricates the lignin parts of the fiber strand, and the unit fiber tends to slide one another. The impact energy absorbed by the composite is higher for OBFP at [0/±45/0̅] 𝑠 fiber orientation which is 16.9J. After the water absorption test, the tensile and flexural strength of OBFP is decreased to 161.92MPa and 124.1 MPa respectively, whereas such properties for laminates of untreated fibers are decreased to 121.4 MPa and 91.8MPa respectively. This is due to the water molecule penetrates the microvoids in the laminate. From the results obtained, it can be generalized as; laminates of oil-treated bamboo fiber have improved tensile, flexural, and impact properties. This is due to the oil wetting the fiber; makes the strand more flexible and lubricates the lignin parts rather than immediate breaking.