Carbon quantum dots represent a fascinating category of carbon nanoparticles with sizes around 10 nm. Carbon quantum dots possess several advantageous characteristics, including environmental friendliness, low toxicity, biocompatibility, photo-induced electron transfer, tunable fluorescent properties, and easily achievable synthesis protocols. These attributes make carbon quantum dots well-suited for a variety of applications, such as photocatalysts, biological imaging, sensing, adsorbents, energy storage and conversion, and wastewater treatment. This chapter covers advancements in carbon quantum dots research and development, with an emphasis on carbon quantum dots synthesis and application in wastewater treatment. Finally, the chapter summarizes challenges and outlines future perspectives to accelerate the further application of carbon quantum dots in wastewater treatment.