Pineapple has been known as one of the most popular tropical fruits in Vietnam with a production of over 674,000 t in 2018. However, by-products from pineapple cultivation account for approximately 65 % of the fresh fruit weight and are mostly being dumped, decomposed or burnt now. Therefore, it has recently raised great concern about environmental pollution. For the first time, extracted fibres from pineapple leaves being utilized for developing successfully eco-friendly and cost-effective pineapple fibres (PFs) aerogels by using polyvinyl alcohol as a cross-linker and following a freeze-drying method. The morphology of the PFs aerogels can be controlled well by changing the PFs concentration (0.5 - 2.0 wt%). The PFs aerogels exhibit extremely low densities (12.7 - 32.6 kg/m3) and high porosities (96.9 - 98.8 %). The BET result shows that the surface area of the PFs aerogel has up to 5.6 m2/g and their pore size of 1.3 - 2.2 nm. The developed PFs aerogels show extremely low thermal conductivities ranging from 0.030 to 0.034 W/m.K. Due to the low Young’s modulus values ranging from 0.47 - 7.86 kPa, the PFs aerogels are flexible and can be used for heat insulation of the buildings as well as food preservation.