A deep eutectic solvent (DES) based on choline chloride and malonic acid was prepared easily with high purity at a low cost. It has been applied as a dual catalyst and reaction medium for the synthesis of functionalized pyrroles by a one-pot, four-component reaction of amines, aldehydes, 1,3-dicarbonyl compounds and nitromethane. This green solvent could be recycled and reused three times without loss of its efficiency.