In this work, a few layer molybdenum disulfide (MoS₂) and reduced graphene oxide (rGO) nanocomposite have been synthesized by liquid exfoliation method. The morphological and structural properties are analyzed using scanning electron microscopy and X-ray diffraction technique. The optical properties are also investigated using absorption and Raman spectroscopy. This report presents quantification of swift heavy ion irradiation induced defects using Raman spectroscopy. We found both Raman mode E¹_2g and A_1g corresponding to MoS₂ and Raman modes of rGO are strongly affected by increasing ions doses. The defect induced lattice strain in the rGO/MoS₂ nanocomposite is also estimated from Raman spectroscopy. MoS₂ layers are found to be much more sensitive than rGO in the rGO/MoS₂ nanocomposite. These types of study further used in device based application of rGO/MoS₂ nanocomposite system.