Nowadays, many concerns are arising about fire risks due to the use of polymers as flammable materials. Incorporating fire retardant (FR) materials with polymer matrix is an effective approach to enhance the performance of polymers against fire. Although halogen-based FRs have represented undeniable performance in reducing polymer flammability, many concerns have been raised due to environment and human health-associated risks. Therefore, halogen-free alternatives have drew attentions in this regard. However, they should be incorporated in higher amounts to enable meeting fire standards and safety regulations. This not only adversely affects the polymer properties including mechanical properties but also dramatically reduces polymer foamability. To overcome the detrimental effect of high loading of FR on polymer foaming behaviour, it is claimed that nano-fibrillation technology can effectively enhance polymer foamability by improving the melt strength of the polymer matrix. Thus, this study aims in developing nano-fibrillated polymer composites with enhanced foaming ability with fire retarding characteristics. Polystyrene, Teflon (PTFE) and Expandable Graphite (EG) are main matrix, fibril phase and FR, respectively. It is firstly showed how increasing EG content from 0 to 40 wt% reduces matrix foamability. The effectiveness of nano-fibrillation in improving the foaming behaviour of highly-filled composites will be demonstrated by measuring cell density, cell size and expansion ratio. Finally, enhanced fire retarding properties of the composite is expressed with well-known burning tests such as UL-94 and Limiting Oxygen Index (LOI).