In this work, a task-specific ionic liquid 1-methyl-3-butylimidazolium hydroxide [Bmim]OH has been used as a potential greener solvent for Cu-catalyzed azide–alkyne cycloaddition reaction (CuAAC) and provides a simple way to access 1,4-disubstituted 1,2,3-triazoles regioselectively with excellent yields, without requiring bases, reducing agents, ligands or inert atmosphere. Moreover, a one-pot three component CuAAC reaction was developed using alkyl bromide, sodium azide, and terminal alkyne affording 1,2,3-triazoles in high yields.