Core/shell wormlike polymer brushes with densely grafted poly(?-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) are synthesized via grafting an alkynyl terminated PCL-b-PEO (ay-PCL17-b-PEO113) onto a well-defined azido functionalized polymethacrylate (PGA940) and are evaluated preliminarily as a single molecular cylindrical vehicle for drug delivery. Water soluble molecular worms of ca. 230 nm are obtained and then the anticancer drug doxorubicin (DOX) is loaded into its PCL core by hydrophobic interaction. Compared with spherical micelles from linear PCL17-b-PEO113, the brushes demonstrate a lower loading efficiency but a faster release rate of DOX. Confocal laser scanning microscopy measurements show that DOX-loaded cylindrical molecular brushes can easily enter into HeLa and HepG2 cells in 1 h.