The present work investigates the effect of novel biofiller, crystalline silk nano-discs (CSNs)', on thermal stability and crystallization behaviour of melt-processed poly (lactic acid) (PLA)/CSN nanobiocomposites which are very much important for polymer processing. The PLA/CSN nanobiocomposites are obtained through melt extrusion technique. Thermogravimetric (TGA) data revealed that incorporation of1 wt.% CSNs in PLA enhanced onset degradation temperature (T-onset)10 degrees C, and this improvement in thermal stability is due to the formation of network-like structures. Activation energies (E-a) of nanobiocomposites, determined from model-free (Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose methods) and model fitting (Coats-Redfern method) approaches, increased in comparison with PLA, indicating that CSNs impede thermal degradation process. Possible mechanism is proposed for thermal degradation process of nanobiocomposites using Criado's method. Hyphenated TGA-Fourier transform infrared is utilized to identify evolved gaseous products during degradation of silk, CSNs, PLA and nanobiocomposites. Differential calorimetry data was analysed by Jeziorny, Liu-Mo and Tobin models. It was found that CSNs act as heterogeneous nucleating agents, hence improve non-isothermal crystallization kinetics of PLA.