Two dimensional materials such as graphene and transition metal dichalcogenides (TMDC) have gained profound research interest as novel optical material owing to their remarkable optical and electrical properties. The formation of atomically controlled van der Waals (vdW) heterostructured architectures facilitates comprehending innovative photosensing and optoelectronic devices exhibiting unique properties than conventional counterparts. We have demonstrated the use of MoS2/graphene heterostructured field effect transistor (FET) for photosensing applications. For different drain to source voltages (V-ds), the effect of DUV irradiations is studied, revealing an increased photoresponse. Optical performance of FET is studied by evaluating photoresponsivity (R-lambda), detectivity (D*) and external quantum efficiency (EQE). Optical response with R-lambda and D* approaching 3.34 x 10(3) AW(-1) and 1.004 x 10(12) jones, respectively is obtained. This approach of creating TMDCs/graphene based heterostructured devices provide new insights for development of high performance photosensors for next generation optical and sensing applications.