Near-ultraviolet organic light-emitting diodes (NUV-OLEDs) with emission below 400 nm are promising candidates for compact ultraviolet light sources, yet their performance is often limited by the scarcity of efficient wide-bandgap emitters and the presence of severe charge-injection/transport imbalance. This work demonstrates an effective strategy for optimizing charge balance for NUV-OLEDs by exploiting 9-3-(9H-carbazol-9-yl)phenyl-3-(diphenylphosphoryl)-9H-carbazole (mCPPO1), a bipolar host widely used in deep-blue phosphorescent OLEDs, as a near-ultraviolet fluorescent emitting material and by introducing a bipolar dopant, 2,6-bis3-(9H-carbazol-9-yl)phenylpyridine (26DCzPPy), to regulate carrier transport in the emitting layer. All devices were fabricated on indium tin oxide (ITO) substrates via high-vacuum (< 2×10^-4 Pa) thermal evaporation. A reference device employing neat mCPPO1 as the emitting layer exhibited a stable electroluminescence peak at 374 nm with negligible long-wavelength parasitic emission; however, its electrical and efficiency with a maximum radiant power density of 11.26 mW·cm^-2 and an external quantum efficiency (EQE) of only 1.6%, showing pronounced efficiency roll-off. To address this limitation, a series of doped emitting layers, 26DCzPPy(x wt%):mCPPO1 (x = 5, 10, 15, 20), was constructed, where 26DCzPPy also serves as a hole-transport “ladder” due to its matched frontier orbital levels relative to the adjacent transport layers. Systematic device characterization, including current density-voltage-radiant power-EQE measurements, electroluminescence spectra, single-carrier devices, and transient photoluminescence decay, revealed that moderate 26DCzPPy doping markedly enhances electron transport, mitigates interfacial carrier accumulation, and broadens the effective recombination zone, thereby improving exciton utilization. The optimal doping concentration is 10 wt%, at which the device achieves an EQE of 3.56% and a peak radiant power density of 57.84 mW·cm^-2, while maintaining high spectral purity; the integrated spectral contribution below 400 nm reaches 68.37%. Transient photoluminescence analysis further shows that the exciton lifetime increases from 15.38 ns (neat mCPPO1 film) to 23.28 ns at 10 wt% doping, indicating suppression of nonradiative decay channels and improved carrier balance. In contrast, excessive doping (≥ 15 wt%) introduces additional energetic disorder and loss pathways, leading to reduced current output and degraded efficiency. Finally, the stability of the devices was tested. Compared with the undoped device, the doped devices showed a substantial improvement in stability. These results verify that dopant-enabled carrier-balance engineering is an effective route to enhance NUV-OLEDs performance and highlight a practical approach to repurposing deep-blue bipolar host materials as near-ultraviolet emitters.