A simple technique to synthesize and functionalize kaolinite nanoparticles having analogous shape and size in single step using layered silicate microclay as starting material is presented. The morphology, composition, and functionalization study of the activated nanokaolinite were determined by scanning electron microscopy/energy-dispersive spectroscopy, atomic-force microscope, and Fourier transform infrared spectroscopy, correspondingly. Various concentrations of activated nanokaolinite were doped in acrylonitrile butadiene rubber (NBR) by conventional industrial elastomeric mixing techniques to fabricate composite specimens. The accumulated data simulated that the thermal conductivity was diminished 92 % by increasing 15 mass% filler loading in the polymer matrix. Thermogravimetric analyzer showed that thermal stability and heat-absorbing capability were remarkably augmented by increasing activated nanokaolinite concentration in the NBR base formulation. Differential scanning calorimetric study revealed that glass transition and crystallization temperatures were reduced, whereas first and second melting phase temperatures were enhanced by increasing filler-to-host matrix ratio. Tensile strength, elongation at break, and elastic modulus at 200 % elongation were remarkably improved to a level of 144, 66, and 90 %, respectively, with increasing filler-to-matrix ratio. Efficient enhancement in elastomeric hardness was also observed.