Polymer composites were prepared successfully by combining tea waste, resulting from agricultural product processing, which was used as reinforcement material and biodegradable polymers which was used as matrix material. Chitosan and poly L-lactic acid were used as biodegradable polymers. Sodium tripolyphosphate and borax pentahydrate were chosen as composite additives. Optimization studies were done on the processing parameters and the characterization results obtained from infrared spectra, X-ray diffractograms and thermograms could be used to evaluate the prepared polymer composites for potential applications like food packaging/coating or disposable medical products etc. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses indicated that additives improved the interaction of the tea waste and the polymers. Thermal stability of chitosan was enhanced by preparing a composite with tea waste. The water resistance behavior of the prepared polymer composites increased.