An organic light-emitting device is provided to have high efficiency and long lifespan. The organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; an emission layer disposed between the first electrode and the second electrode and including a host and a dopant; an electron blocking layer disposed between the first electrode and the emission layer; and an electron transport region disposed between the emission layer and the second electrode, in which the electron blocking layer includes a metal halide, a metal oxide, or a combination thereof, and the actually measured lowest unoccupied molecular orbital (LUMO) value of the electron blocking layer is greater than the actually measured LUMO value of the host in the emission layer.