Polylactic acid (PLA), one of the widely studied renewable resource based biopolymer is yet to gain a strong commercial standpoint. Slow crystallization rate in PLA have known to impart poor mechanical performance and durability. Hence, this work attempted to enhance the performance of PLA biocomposites where toughened PLA based ternary blend served as a matrix material for incorporation of miscanthus fibers. Effect of adding various nucleating agents promoted specifically for PLA at different loading levels were investigated. The crystallinity was controlled by optimizing injection molding parameters such as melt temperature profile, mold temperature and cooling time. Concurrent improvements in impact strength and heat deflection temperature (HDT) have been successfully achieved in PLA based biocomposites. Optimized processing parameters, and choice of effective compatibilizers and nucleating agents have lead to a 3 fold increase in impact strength with 60% increment in HDT compared to neat PLA, while maintaining a renewable material content of 75%. Dramatic increase in crystallization rate and crystalline content was observed from isothermal and nonisothermal crystallization measurements. The spherulite sizes in PLA composites with and without the nucleating agents were also measured using polarized optical microscopy. Acknowledgments The authors gratefully acknowledges the funding of Ontario Ministry of Agriculture & Food (OMAF) and Ontario Ministry of Rural Affairs (MRA)-New Directions Research Programs 2010, Natural Sciences and Engineering Research Council (NSERC) NCE AUTO21 program and Ontario Research Fund, Research Excellence Program, Round-4 (ORF-RE04) from Ontario Ministry of Economic Development and Innovation (MEDI).