A new heterogeneous nanocatalyst (Fe3O4@SiO2-Schiff base-Co(II)) was successfully fabricated applying silica-coated magnetite nanoparticles as a suitable and efficient support for covalent anchoring of a cobalt(II) Schiff base complex. This catalyst was characterized by FT-IR, XRD, SEM, TEM, EDX, ICP-OES, CHN, DRS, TGA, VSM techniques, and QM study. According to theoretical calculations, the Schiff base-Co(II) complex at high spin state with square planar geometry is more stable than low spin state. Also, Schiff base-Co(II)/imidazole complex has distorted square pyramidal geometry. Evaluating the activity of the nanocatalyst was performed for the oxidizing of different olefins (styrene, norbornene, α-methyl styrene, cyclohexene, and cyclooctene) and alcohols (benzyl alcohol, benzhydrol, n-butanol, n-octanol and n-heptanol). In these reactions, the influence of two various oxidants, molecular oxygen and tert-butyl hydroperoxide (TBHP), were examined. The results exhibited that the nanocatalyst was considerably effective for the aerobic epoxidation of norbornene, cyclohexene, and cyclooctene with 100% conversion and selectivity within 1 h. Also, by oxidizing of benzyl alcohol and benzhydrol, benzoic acid (conversion: 94%, selectivity: 91%) and benzophenone (conversion and selectivity: 100%) were achieved, respectively. The results suggested that the nanocatalyst has a remarkable role in oxidation reaction of olefins and alcohols. Other promising advantages of the catalyst were easy magnetic separation and recyclability for several times without significant loss of catalytic efficiency.