Abstract In this work, highly efficient pure fluorescent white organic light-emitting diodes (WOLEDs) are realized through the structural design by employing thermally activated delayed fluorescence (TADF) molecule of mSOAD as blue emitter and exciplex donor, respectively. The combination of mSOAD: PO-T2T exhibits yellow-green exciplex emission with high EQE of 9.7%. Based on the application of this exciplex as the host, the high efficiency WOLEDs with current efficiency, power efficiency and external quantum efficiency (EQE) of 30.2 cd A−1, 28.0 lm W−1 and 11.6%, respectively, are achieved finally. Meantime, stable warm white emission spectra with Commission Internationale de l'Eclairage (CIE) coordinates change as low as (0.030, 0.008) from 5 V to 8 V are also realized. The reasonable structural design and double functions application of TADF molecule are responsible for the high performances fluorescent WOLEDs.