The present disclosure relates to an organic light emitting diode including an emitting material layer that has a host and two different delayed fluorescent materials whose energy levels are controlled and an organic light emitting device including the diode. Exciton energy is transferred from a first delayed fluorescent dopant to a second delayed fluorescent dopant, which has singlet and triplet energy levels lower than singlet and triplet energy levels of the first delayed fluorescent dopant and a narrow FWHM (full-width at half maximum) compared to the first delayed fluorescent dopant so that efficient light emission can be realized.