An efficient approach to prepare carbon nanotube-gold nanoparticle nanocomposites was reported by using amphiphilic copolymer containing coumarin. Amphiphilic copolymer PSVM was synthesized by addition-fragmentation chain transfer (RAFT) polymerization and was employed to functionalize pristine MWNTs (multiwalled nanotubes). Gold nanoparticles (AuNPs) synthesized by an in situ reduction approach were then strongly anchored on the functionalized MWNTs. This technique provided a simple and convenient route to efficiently assemble AuNPs onto the surfaces of MWNTs.