A series of mesoporous organosilicas with different phenyl group content have been synthesized for the immobilization of Heme proteins. A higher number of phenyl groups are conducive to immobilization of Heme proteins and improvement of the activity of the immobilized enzymes. The amount of immobilized horseradish peroxidase (HRP), myoglobin (Mb) and hemoglobin (Hb) is 35 mg, 51 mg and 244 mg, respectively, with 1 g of mesoporous organosilica. In particular, the immobilization efficiency of Mb can reach 100%. A sensor utilizing HRP immobilized in mesoporous organosilica is constructed on a glassy carbon electrode. In buffer solution (pH 6.0), the modified electrode shows an electrochemical response towards catechol.