In this study, our focus is on the compatibility behaviour of bio-based polyester blend with the addition of surface-modified oil palm fruit bunch fibres (OPFBFs). The surface of OPFBF has been modified using alkali, silane and acetic anhydride solutions. Surface-modified fibres are characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy analyses to identify the functionality, adhesion and phase morphology. Untreated and treated fibres are incorporated in the bio-based polyester blend with about 30% of fibre content. Surface-modified fibre biocomposites exhibit improved interaction between the polymer matrix and the fibre. Oil palm fibre-reinforced biocomposites exhibit enhanced thermal, mechanical and morphological properties with incorporation of surface-treated fibre. The OPFBF also acts as a reinforcement filler and adhesion material for the polyester blend.