To endow enhanced tumor specificity and endosome disruption property on the carrier, a multifunctional polymeric micelle was investigated. The micelle exposes the cell interacting ligand (biotin) on the surface under slightly acidic environmental conditions of various solid tumors and is internalized by biotin receptor-mediated endocytosis in a short time period. The micelle also showed pH-dependent dissociation, causing the enhanced release of doxorubicin from the carrier in early endosomal pH. The dissociated micellar components subsequently disrupt endosomal membrane.