<p>Mercury contamination poses a significant environmental and health hazard due to its high toxicity and bioaccumulative nature. The development of highly selective and sensitive sensors for Hg²⁺ ion detection has gained immense research interest. Among various chemosensors, imidazole-based fluorescent sensors have emerged as promising moiety due to their unique electronic properties, strong metal-binding affinity, and tunable fluorescence response. This review comprehensively explores the recent advancements in imidazole-functionalized fluorescent probes for Hg²⁺ sensing, highlighting different design strategies, sensing mechanisms, and structure–property relationships. This review comprehensively summarizes recent progress in the design and development of imidazole-based fluorescent probes for Hg²⁺ detection. Various sensing mechanisms including fluorescence quenching (OFF), fluorescence enhancement (ON), and ratiometric approaches are discussed in relation to their molecular design and structure–property correlations. The analytical performance of these probes is evaluated in terms of sensitivity, selectivity, response time, and applicability in complex sample matrices.</p> Graphical Abstract <p></p>