In the field of targeted drug delivery, quantum dots (QDs) have emerged as the most promising tool with their peculiar optical and electronic properties. As a versatile platform for the advancement of nanoparticle-mediated drug delivery (NMDD) systems, the efficacy and precision of therapeutic interventions are enhanced by QDs, which are nanoscale semiconductor crystals. The sophisticated role of QDs in drug delivery is delved into in this chapter, especially with a focus on their application in targeting specific disease sites, such as cancerous tissues. The controlled release of therapeutic agents is not only permitted by the integration of QDs into drug delivery vehicles but synchronous diagnostic imaging is also enabled, thereby transversing the gap between therapy and diagnostics (theranostics). The principles of QD design and biofunctionalization that are critical for minimizing toxicity and enhancing biocompatibility are explored. Additionally, the potential of QDs in overcoming the challenges of traditional drug delivery systems, such as limited bioavailability and off-target effects, is discussed. The chapter concludes with an aspect on the future prospects of QDs in clinical applications, spotlighting their potential to revolutionize targeted drug delivery and personalized medicine.