Cobalt ferrite nanoparticles loaded on multiwalled carbon nanotube (MWCNT) magnetic hybrids have been demonstrated to be promising magnetic resonance imaging contrast agents and drug carriers. However, the hydrophobic, less biocompatible characteristics and low loading capacity for the drug hamper their wide biological applications. To solve the above problem, an alternative strategy is to coat the MWCNTs@CoFe2O4 nanoparticles with a mesoporous silica (mSiO2) shell. Herein, the reasonable fabrication process results in successful coating mSiO2 on the as-obtained MWCNTs@CoFe2O4 nanoparticles, forming well-defined core-shell-structured MWCNTs@CoFe2O4@mSiO2 nanocomposites. The as-synthesized mesoporous nanocarrier possesses a high surface area and large pore volume for the loading of the drug, and has a superparamagnetic feature for drug targeting. Moreover, the anticancer drug doxorubicin (DOX)-loaded MWCNTs@CoFe2O4@mSiO2 nanoplatforms show an excellent pH-responsive drug release character within 48 h. Therefore, a novel nanocarrier based on MWCNTs@CoFe2O4@mSiO2 was proposed, and its potential application for targeted cancer therapy was highlighted.