The synergistic effect produced by ionic liquid extractants in the field of adsorption is first reported here. The data from this work show that the distribution coefficient and synergistic enhancement coefficient of Lu(III) extracted by [P66614][EHEHP] and [N1888][BTMPP] in impregnated resin are pronouncedly higher than those in solvent extraction. The synergistic interplay of combined acid–base coupling bifunctional ionic liquids (ABC-BILs) is the key to the higher adsorption efficiencies of REEs. Moreover, no third phase was observed in the adsorption systems. The elimination of the third phase from ABC-BIL is a remarkable advantage of adsorption over solvent extraction in the present study. This paper reveals efficient and environmently friendly potentials in both of academic research and industrial application for REEs adsorption.