Giant and stable worm micelles formed from poly(ethylene glycol) (PEG)-based diblock copolymer amphiphiles have the potential advantage compared to smaller assemblies for delivery of a large quantity of hydrophobic drugs or dyes per carrier. Here we show that worm micelles can be targeted to cells with internalization and delivery of nontoxic dyes as well as cytotoxic drugs. Constituent copolymers are end-biotinylated to mediate high affinity binding of worm micelles to both avidin-bearing surfaces and biotin-specific receptors on smooth muscle cells. Pristine worm micelles, that lack biotin, show much less frequent and nonspecific point attachments to the same surfaces. Biotinylated worm micelles prove stable in aqueous solution for at least a month and also prove capable of loading, retaining, and delivering hydrophobic dyes and drugs. The results thus demonstrate the feasibility of targeted delivery by polymeric worm micelles.