Flower-like nanostructured hydroxyapatite hollow spheres (NHHS) assembled with nanosheets with a hierarchical morphology are fabricated by a rapid microwave-assisted hydrothermal route. The presence and concentration of block copolymer poly(lactide)-block-poly(ethylene glycol) (PLA-PEG) are important parameters for the formation of the hollow structure. The possible formation mechanism of NHHS is proposed. The NHHS are explored as anticancer drug carriers for cellular delivery of mitoxantrone (MIT). The MIT-loaded NHHS exhibit sustained-drug-release behavior in vitro and the intracellular drug-distribution tests indicate that the MIT loaded in NHHS carriers can enter the cells efficiently. The experiments also show that the NHHS have a good biocompatibility, and therefore, they are promising anticancer drug carriers in cancer chemotherapy.