An organic light-emitting device includes: a first electrode; a second electrode; and an organic layer between the first electrode and the second electrode, the organic layer including an emission layer, wherein the emission layer includes a first host and a dopant, the first host is represented by one selected from Formulae 1 and 2, and the dopant is represented by Formula 7: Ar11(L11)a11-(R11)b11]n11  Formula 1 Ar21(L21)a21-(R21)b21]n21  Formula 2 M(L1)n71(L2)n72.  Formula 7 The organic light-emitting device may have high efficiency and long lifespan and may show little change in the efficiency at an x-coordinate (CIEx) value of 0.21.