A heterocyclic compound represented by Formula 1 and an organic light-emitting device including the same are provided: When the nitrogen atom of the acridine moiety is combined (e.g., coupled) with an sp2 carbon atom of the pentagonal ring, either directly or through a pi-conjugated carbocyclic group, the compound may be electron rich and may easily transport charges. The heterocyclic compound represented by Formula 1 may be used as a delayed fluorescence emitter in the organic light-emitting device, and the device may have a low driving voltage, a high efficiency, a high luminance, and a long lifespan.