Developing catalysts with unique compositional and structural characteristics, high cost-efficiency, and preferable catalytic performance are still an ongoing task for the selective oxidation of alkenes. Herein, we report the facile construction of uniform magnetically separable CoFe2O4 nanoparticles, which can function as an efficient and robust catalyst for the selective epoxidation of styrene with tert-butyl hydroperoxide as the oxidant. This bimetallic catalyst significantly outperformed its monometallic counterparts with respect to Co3O4 flakes and Fe2O3 rods both in terms of total activity and epoxide production. In the presence of CoFe2O4 nanoparticles as the catalyst, the yield of styrene oxide (SO) can achieve 79.7% with a total styrene conversion of 96.4% and a selectivity of 82.7% to SO under the optimal reaction condition. In addition, the activation energy was measured, and a plausible reaction mechanism was proposed. The outstanding catalytic performance of the CoFe2O4 catalyst can be ascribed to the synergistic effects regarding the abundant surface metal redox couples induced by the bimetallic nature and the mesoporous structure with high surface area.