Semiconductor nanoparticles with very small sizes of 2–20 nm (quantum dots) are very much attractive for their excellent photoluminescence property. Herein, this study portrays the green synthesis of highly fluorescent, water-soluble, semiconducting CdSe quantum dots (CdSe QDs) as the most potential cellular imaging tag. The stability of CdSe quantum dots has been achieved by capping with mercaptopropionic acid (MPA) as a stabilising agent, and then biotin was attached to quantum dots after surface modification with streptravidin to attain selective cancer cell targeting ability with enhanced conjugation efficiency, which can result in the easy detection of cancer cells growing in our body. The formation of the desired biotin-conjugated highly luminescent CdSe quantum dot has been well justified by photoluminescence (PL), ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The cancer cell imaging quality of the biotin-conjugated CdSe QD has been assessed with respect to the Human Epitheloid Cervix Carcinoma (HeLa) cell. Cytotoxicity and cellular imaging results in both cancerous HeLa and normal HEK-293 cells revealed the efficiency of this material as an imaging probe.