Using electron paramagnetic resonance and density functional theory calculations, we show that the shallow donor responsible for the n-type conductivity in natural MoS₂ is rhenium (Re) with a typical concentration in the low 10¹⁷ cm^–3 range and the g -values: g_|| = 2.0274 and g_⊥ = 2.2642. In bulk MoS₂, the valley–orbit (VO) splitting and ionization energy of the Re shallow donor are determined to be ∼3 meV and ∼27 meV, respectively. Calculations show that the VO splitting of Re approaches the value in bulk if the number of MoS₂ layers is larger than four and increases to 97.9 meV in a monolayer.