Chitin, a functional carbohydrate derived from waste products of seafood industry, contains abundant nitrogen, which makes it become a very suitable carbon precursor for the synthesis of carbon quantum dots (CQDs). Demonstrated in this work was synthesizing CQDs using this N-enriched primary feed-stock. The as-prepared N-doped carbon quantum dot(N-CQDs) showed both photoluminescence exposed to UV radiation and a good potentiality in fluorescent sensor for detecting of ClO−. Significantly, the detection limit of ClO− was 1.47 μM and its linear range was 0–50 μM (R2 = 0.9922). In addition, the structures and properties of the N-CQDs were further investigated. As indicated in the results, the N-CQDs exhibited a spheroidal morphology with an average diameter of 4.21 nm. Its quantum yield was 25.8%. Moreover, the N content of this N-CQDs increased to 9.89%, consisting of multiple functional groups such as N, CN and NH.