Environmentally friendly and biocompatible tungsten disulphide inorganic nanotubes (INT-WS2) were introduced into a poly(l-lactic acid) biopolymer matrix to generate novel nanocomposite materials through an advantageous melt-processing route. The effects of INT-WS2 on isothermal crystallization and melting behaviour of PLLA have been investigated. INT-WS2 has excellent acceleration effectiveness on the melt-crystallization of PLLA better than the promising nano-sized fillers reported in the literature (e.g. carbon nanotubes, graphene oxide, cellulose nanocrystals). In particular, the addition of INT-WS2 remarkably influences the energetics and kinetics of nucleation and growth of PLLA, reducing the fold surface free energy by up to 18 %. In the same way, the final crystallinity and subsequent melting behaviour of PLLA were controlled by both the incorporation INT-WS2 and variation of the crystallization temperature. These observations will enable the development of novel melt-processable PLLA/INT-WS2 nanocomposites with improved crystallization behaviour for many eco-friendly and biomedical applications.