Over the past two decades, fluorescent quantum dots (QDs) have been highly attractive for a myriad of bioapplications due to their unique optical properties. For bioimaging applications, QD-based in vivo specific tumour targeting is vitally important in the biological and biomedical fields. Aqueous synthesized QDs (aqQDs) exhibit excellent aqueous dispersibility without requiring any post-treatment and have small hydrodynamic diameters (generally <5 nm), which are highly useful for bioimaging applications. We herein present the first example of in vivo active tumour targeting using water-dispersed near-infrared-emitting aqQDs modified with Arg-Gly-Asp (RGD) peptides. In vitro and in vivo studies (e.g., tumour cell labelling, histological analysis, and active tumour targeting) demonstrate that the prepared RGD-decorated aqQDs exhibit highly bio-specific properties, enabling sensitive and specific targeting of tumour sites in both cells and living animals. Our results suggest that the new class of RGD-decorated aqQDs are highly promising as fluorescent bioprobes for a wide range of biological applications.