A green, sustainable, and efficient one-pot, synthetic strategy for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones (DHQs) was developed. The ZnCl2/urea used as a deep eutectic solvent (DES) not only efficiently promoted the condensation between isatoic anhydride and benzaldehyde but unexpectedly acted as a nitrogen source (like ammonia) in situ to afford DHQs in excellent yields. This approach offers remarkable advantages, involving the triple role of DES in the synthesis of DHQs, atom-economical, green organocatalysts, metal-free conditions, cost-effectiveness, and tolerance to a range of functional groups. [ABSTRACT FROM AUTHOR]