<p>Nitrite (NO₂⁻) is widely present in water and commonly used in food products. Excessive ingestion of NO₂⁻ poses significant hazards to human health. Therefore, the development of accurate and sensitive nitrite detection methods is greatly essential for public health safety. Herein, novel red-emitting carbon dots (r-CDs) with a narrow emission width (45nm) were prepared through a simple hydrothermal reaction. The fluorescence of r-CDs at 628 nm could be directly and gradually quenched by NO₂⁻_. Thus, a highly sensitive and selective nitrite sensing platform was constructed with a wide linear concentration range of 3–200 µM and a detection limit of 0.85 µM. Satisfactory detection performance of NO₂⁻ was verified in meat, water, milk, and pickled vegetable samples. Furthermore, this probe was successfully applied in distinct fluorescence imaging, exhibiting great potential for the intracellular analysis of NO₂⁻. In conclusion, this narrow-emission NO₂⁻ sensor features facile synthesis, good anti-interference capability, and a wide application scope.</p> Graphical abstract <p></p>