Carbon dot-metal/metal oxide nanocomposites (CMN) are gaining attention in designing efficient catalytic systems where the water soluble Carbon dots (CDs) show dual functionality of a stabilizing agent as well as a reducing agent for the generation of metal nanoparticles in situ. The CDs in the nanocomposites, not only help in modulating electronic band structures of metal/metal oxides by its unique electron transfer property but they are also expected to significantly influence on their morphology and surface properties. Herein, we report the synthesis of CDs – Gold (CDs-Au) nanocomposites through solution method and have explored their catalytic property in the reduction of Nitroaromatics (NAs). The CDs, synthesized through microwave pyrolysis of a mixture of Citric acid(CA) and thiourea, were dissolved in Millipore water and then added into aqueous solution of HAuCl4 to obtain a solution of the CDs – Au nanocomposites. The synthesized CDs and colloidal solution of CDs - Au nanocomposites were characterized in detail using UV-Vis spectroscopy, FT IR, XRD, TEM, HRTEM, EDX and XPS analysis. The catalytic efficacy of the CDs – Au nanocomposites were premised on real time monitoring of the reduction of NAs such as 4-Nitrophenol (4-NP), 4-Nitroaniline (4-NA) and Nitrobenzene (NB) by NaBH4 using UV–Visible absorption spectroscopy. The apparent rate constants (Kapp) of reduction of the NAs in the presence of the nanocatalysts were found to follow the pseudo-first-order kinetics having value of 1.37 × 10-1 , 8.9 × 10-2 and 5.35 × 10-2 s-1 for 4-NP , 4-NA and NB repectively. The apparent rate constant (1.37 × 10-1 s-1) observed for the reduction of 4-NP by NaBH4 using CDs – Au nanocomposites has been found to be one of the highest values reported in literature so far thereby establishing nanocomposites their excellent efficacy as an catalyst.