Highly efficient and sustainable conversion of CO₂ into quinazoline-2,4(1H,3H)-dione at room temperature and atmospheric pressure is challenging. Deep eutectic solvents (DESs) are considered as the green solvents of the 21st century, which are also designable with high tunability and high atom efficiency. Here, DESs are for the first time used to catalyze the CO₂ conversion into quinazoline-2,4(1H,3H)-dione at room temperature and atmospheric pressure with high efficiency and nearly 100% yield. This work provides a sustainable way for the efficient conversion of CO₂ into quinazoline-2,4(1H,3H)-dione by DESs at room temperature and atmospheric pressure.