A one-pot sonochemical method was developed for the green synthesis of highly fluorescent carbon dots with nitrogen dopants ([email protected]) derived from crab shells. The synthesized [email protected] exhibited excellent water solubility with a fluorescence quantum yield of 14.5%. The [email protected] then conjugated with folic acid (FA) to construct the [email protected] nanoprobe with the ability to selectively target folate-receptor positive cancer cells. Moreover, in vitro cytotoxicity studies showed excellent biocompatibility. Cellular uptake of the [email protected] was further studied via in vitro confocal microscopy studies. Results showed that [email protected] nanoprobes were mostly localized in the cytoplasm of the folate receptor-overexpressing Human cervical cancer cell (HeLa) while cellular uptake by human embryo lung cell (HEL) cells (folate receptor-deficient control) was negligible. Based on their improved diagnostic imaging and enhanced targeting effect, the [email protected] probe has high potential in the theranostic applications. This study demonstrates an economically viable approach to synthesize [email protected] probe using seafood waste.