N‐heterocyclic imines are widely used in transition‐metal chemistry, main‐group chemistry as well as catalysis, due to their enhanced basicity and nucleophilicity which benefit from their ylidic form. As their analogs, mesoionic N‐heterocyclic imines, which feature more highly ylidic form, is still in its infancy though excellent works also achieved. Here we reported the synthesis, characterization and photophysical properties of mesoionic N‐heterocyclic imines. TD‐DFT are employed to get deeper insight into the mechanism of the photophysical behaviors. The unsubstituted mesoionic N‐heterocyclic imines (4–6) displayed considerable quantum yields (QY: up to 43.8%) and could be potentially applied as luminescent materials.