“Hot-exciton” fluorescent materials can efficiently convert triplet excitons into singlet excitons through a path from high-lying triplet excited states (T_n, n > 1) to singlet excited states (S_m, m ≥ 1). The fast reverse intersystem crossing (RISC) process of the hot-exciton channel promotes a high exciton utilization efficiency (EUE) and reduces the efficiency roll-off (η_roll-off) caused by the accumulation of low-lying triplet excitons (T₁). Herein, a pure-blue-emitting molecule, PICNAnCz, exhibiting hot-exciton fluorescent emission is proposed. The optimized PICNAnCz-based nondoped organic light-emitting diode (OLED) device achieves a high external quantum efficiency of 9.05% corresponding to a large EUE of 87% and a low η_roll-off of 13%, achieving both high efficiency and a small η_roll-off. The maximum current efficiency and power efficiency of the nondoped device are 9.07 cd A⁻¹ and 5.76 lm W⁻¹, respectively. The nondoped device shows a novel blue electroluminescence (EL) emission with a peak wavelength of 448 nm and Commission Internationale de l’Eclairage coordinates of (0.16, 0.11). These results are among the best reported for hot-exciton blue-emitting materials for nondoped blue fluorescent OLEDs. The excellent EL performance is attributed to the nanosecond-scale RISC process from the high-lying triplet excited state (T₂) to the lowest singlet excited state (S₁).