In this research an efficient synthesis of a novel nanocomposite including SiO2@(3-aminopropyl)triethoxysilane-coated cobalt oxide (Co3O4) nanocomposite has been reported by three step method. The structure and magnetic characterization of Co3O4@SiO2@NH2 have been done by using various spectroscopic analyses which include FT-IR, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Amino-functionalized SiO2 coated Co3O4 nanocomposite exhibited superparamagnetic behavior and strong magnetization at room temperature. The average crystallite sizes of the Co3O4 are 23.7 nm. The obtained magnetic nanocomposite showed excellent catalytic activity as a new heterogeneous magnetic catalyst for the synthesis of some indazole derivatives under mild reaction conditions along with high level of reusability.