One octopus-shaped amphiphilic polymer was used to functionalize MWNTs for the first time. Characterization results showed that the octopus-shaped amphiphilic polymer was much more efficient at modifying MWNTs than linear polymers in aqueous or acetone solution. The hydrophobic cubic-silsesquioxane core locally anchored to the surface of the nanotubes, while the arms of the RAFT polymer extended into the aqueous solution, thus imparting steric stabilization to the nanotube dispersion.