A light-emitting device includes: a first electrode; a hole injection layer; a hole transport layer; an emission layer; an electron transport region; and a second electrode, stacked in order, wherein the hole transport layer and the hole injection layer are different from each other, the hole injection layer includes a first inorganic material, the first inorganic material is an oxide of at least one metal selected from tungsten (W), molybdenum (Mo), zinc (Zn), copper (Cu), nickel (Ni), cobalt (Co), gallium (Ga), and germanium (Ge), the first inorganic material has a work function with an absolute value of about 4.3 eV to about 5.3 eV, and the hole injection layer and the hole transport layer satisfy Equations 1 and 2: |ELUMO_HIL|>|ELUMO_HTL|+0.1 eV  Equation 1 |EHOMO_HIL|>|EHOMO_HTL|+0.1 eV.  Equation 2