In this work, synergistic reinforcing effects of molybdenum disulfide (MoS2) and bentonite in nitrile butadiene rubber (NBR) based nanocomposites was studied. The friction coefficients of the nanocomposites were significantly decreased as MoS2 was applied as a lubricant while the reinforcing effects of MoS2 on the tensile strength of neat NBR at a loading of 5 phr was marginal. However, with MoS2 added in bentonite/NBR nanocomposite, the 300% modulus was remarkably enhanced. The synergistic reinforcing effects were more prominent in the aspect of storage modulus both in rubbery region and glassy region. Meanwhile, with MoS2 incorporated, the glass transition temperature (Tg) was elevated up to -19.7 and -6.7 °C, respectively for bentonite/NBR and (3-mercaptopropyl) trimethoxysilane compatibilized bentonite/NBR nanocomposites.