The development of efficient deep-blue to blue emitters is crucial for next-generation optoelectronic materials. In this work, three donor-engineered hybridized local and charge-transfer (HLCT) emitters were rationally designed and synthesized by integrating carbazole (CBZ) and imidazole donor units into a conjugated framework. The molecular design enables effective modulation of the excited-state characteristics through the coexistence of locally excited (LE) and charge-transfer (CT) states, which is advantageous for achieving efficient deep-blue emission. Photophysical investigations reveal that these fluorophores exhibit strong deep-blue to blue fluorescence with high emission efficiency, arising from the HLCT nature of the excited states. Theoretical calculations further confirm the hybridized LE/CT character, indicating an optimal balance between radiative decay and exciton utilization. Owing to their favourable photophysical properties, the emitters were successfully employed as organic downconverter materials for hybrid LEDs. The fabricated devices exhibit stable deep-blue to blue electroluminescence with promising performance. This work demonstrates that strategic donor engineering of imidazole-based frameworks is an effective approach for developing metal-free HLCT emitters for high-performance optoelectronic applications.