An α-tocopheryl succinate (α-TOS) containing diblock copolymer micellar system was used to deliver doxorubicin (Dox), an anticancer drug, for HCT116 colon cancer therapy. The α-TOS containing diblock copolymers were synthesized by conjugation of α-TOS molecules and a mPEG-b-PHEMA hydrophilic diblock copolymer by ester bonds. The Dox-loaded polymeric micelles were then obtained by solvent exchange process. In acidic surroundings such as endosomes or secondary lysosomes, the structures of the Dox-loaded polymeric micelles deformed and released the drug loads. Additionally, Dox-loaded polymeric micelles enhanced the cytotoxicity of Dox and α-TOS to cancer cells in vitro. Dox-loaded polymeric micelles also showed an exceptional tumor inhibiting effect in vivo. This study indicates that the α-TOS containing polymeric micelle system can be used as a drug carrier for cancer therapy.