An organic light-emitting device including a first electrode, a second electrode facing the first electrode, and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer has an emission layer, wherein the emission layer includes a host and a thermally activated delayed fluorescent dopant, wherein the dopant includes a condensed cyclic compound represented by Formula 1, and wherein an amount of the dopant is smaller than that of the host: Ar1—Ar2  Formula 1 wherein Ar1 and Ar2 are the same as described in the specification.