In recent years, the development of high-performance fluorescent organic light-emitting devices(FOLEDs) has attracted extensive attention in both academic and industry research areas. Since only 25% electronically excited excitons can be used for electroluminescence, the external quantum efficiencies(EQEs) of conventional FOLEDs are generally less than 5%. In order to increase the exciton utilizing efficiency for enhanced performance of FOLEDs, the architecture of sensitized FOLEDs(SFOLEDs) are designed to harvest both singlet and triplet excitons by means of efficient energy transfer processes from the host or sensitizer to the fluorescent dopant. Great progress has been made in the efficiency enhancement of FOLEDs and the maximum EQE values of the reported SFOLEDs have reached 26.1% to date. This review intents to introduce the sensitization principles and working mechanisms of various SFOLEDs in detail. Also, the latest research progress on the device structures and performance are summarized and discussed for various SFOLEDs based on thermally activated delayed fluorescent(TADF) sensitization, exciplex sensitization, triplet exciton annihilation sensitization, and hybridized local and charge-transfer(HLCT) sensitization, etc. Finally, the future research directions of SFOLEDs are discussed to give an outlook of the prospect trends and future challenges. We hope that this review attracts more researchers with different disciplinary areas to devote themselves to this interesting research field.