The typical generation efficiency of radiative singlet excitons is limited to only 25% in fluorescent organic light-emitting diodes (LEDs). Here we show that the singlet generation efficiency can be increased to over 25% by incorporating an organic fluorophore with appropriate energy levels into a two-dimensional metal halide perovskite. In our fluorophore-containing perovskite LEDs, carrier transport and exciton formation take place in the perovskite’s metal halide framework, thereby avoiding the formation of nonradiative-triplet excitons on the organic fluorophores. Subsequently, the bright triplet excitons formed in the metal halide framework are transferred to singlet states of the organic fluorophores, leading to efficient electroluminescence from the organic fluorophores inside the perovskite.