A facile route for grafting poly(ionic liquid)s (PILs) on to the surface of multi-walled carbon nanotubes (MWNTs) was demonstrated via Diels-Alder (DA) “click” reaction. Firstly, block copolymers of poly(chloromethylstyrene-alt-maleic anhydride) (PCMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization. The anhydride units in the copolymer were functionalized with furfuryl amine and then the chloromethyl groups were subsequently tailored with 1-methylimidazole, which afforded imidazolium-based PILs bearing pendent furan moieties. The PILs chains were covalently anchored to the surface of MWNTs, affording PILs/MWNTs by the DA reaction in water under ultrasound assistance. The obtained hybrid materials were characterized by TGA, FT-IR, and TEM analysis. The PILs/MWNTs could be well dispersed in water and organic solvents for several months.