The development of natural fibre biodegradable composites are gaining much attention due to lower environmental impact, driven by the issues with synthetic fiber-based polymer composites manufacture, disposal, and recycling. Nowadays, pineapple leaf fibre (PALF) are playing significant role in composites exhibiting superior performance than other cellulose fibres for a variety of uses in the automotive, biomedical, furniture, and packaging industries, among others. This study examined the combined effects of in-house coupling agent production and pineapple leaf fibre (PALF) loading on the mechanical and thermal characteristics of  biodegradable polymers polylactic acid (PLA) and poly(butylene adipate-co-tere-phthalate) (PBAT), which were manufactured by melt compounding. The PLA grafted with maleic anhydride (MA) (PLA-g-MA) was used as a coupling agent to improve the interfacial adhesion between PLA and PBAT with PALF. The results demonstrated the dependence of thermal stability and tensile properties on the grafting level of MA, and also on the concentrations of PALF. Thus, it could be deduced that combination of PALF at high concentrations (5, 10 and 15 wt%) and PLA-g-MA with high grafting level can significantly improve the thermal stability of PLA and PBAT. On the other hand, at high grafting level, there was an improvement in tensile modulus of biocomposite. The morphological analysis indicated better adhesion between PALF and PLA with PBAT, in composites containing PLA-g-MA with high grafting level. Overall, PLA/PBAT/PALF/PLA-g-MA green composites with improved interfacial adhesion, thermal stability and mechanical properties were successfully optimised to replace non-biodegradable conventional plastics with added advantages of biodegradability.