Increasing awareness about global warming and the limited resources of petroleum products has motivated researchers to use natural fiberNatural fiber-based compositesComposite for potential value-added applications. Natural fiberNatural fiber-based compositesComposite are biodegradable, sustainable, and promote the material circular economy. Natural fiberNatural fiber-based compositesComposite are used in various engineering applications, including automobile interior and exterior parts, transportation, sports equipment, and so on since they are of low density, eco-friendly, low cost, easy to produce, and biodegradable. The present work focuses on the effect of the incorporation of different weight percentages of multi-walled carbon nanotubesMulti-walled carbon nanotubes (MWCNTs) on the tensile, flexural, and dielectricDielectric behavior responses of coir fiberCoir fiber (CF)-based polymer compositesComposite. The CF-based polymer compositesComposite are prepared via an in-house hand-layup technique. The uniaxial tensile test as per ASTM D-3039 standard in UTM, 5967 is used to obtain the elastic constants of the prepared compositesComposite. The flexural behavioursFlexural behaviour of the prepared compositesComposite are investigated through the three-point flexural test as per the ASTM D-790 standard. The fiber and different weight percentages of MWCNTs dispersion in the matrix and their morphology are investigated through scanning electron microscope (SEM). The results of this study may lead to the emergence of novel materials that are environmentally friendly and highly effective, supporting the global movement toward sustainable engineering methods.