Two-dimensional transition metal dichalcogenides (2D-TMDs) have been proposed as novel optoelectronic materials for space applications due to their relatively light weight. MoS2 has been shown to have excellent semiconducting and photonic properties. Although ionizing gamma radiation can strongly interact with bulk materials, its effect on atomically thin materials has scarcely been investigated. Here, we report the effect of gamma irradiation on the structural and optical properties of a monolayer of MoS2. We perform Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) studies of MoS2, before and after gamma ray irradiation with varying doses. The Raman spectra and XPS results demonstrate that point defects dominate after the gamma irradiation of MoS2. To understand electronic properties, we perform density functional theory (DFT) calculations.