The inherent low activity at room temperature has greatly limited the utilization of Co3O4 in indoor air purification. In this work, an extremely facile and mild method utilizing the strong oxidation of H2O2 was designed to prepare a novel Co3O4-HP catalyst. The Co3O4-HP catalyst exhibits excellent removal activity for low-level concentration (similar to 1 ppm) of formaldehyde (HCHO) at room temperature. Under the static test mode, it shows 90.62% HCHO removal efficiency in 180 min at an RH of similar to 55%. Under the dynamic test mode, it maintains the performance to remove approximately 97.26% of HCHO within 180 min under a GHSV of similar to 90,000 mL.h(-1).g(-1). Additionally, the HCHO removal efficiency of Co3O4-HP is also maintained at around 94.76% under a higher GHSV of similar to 150,000 mL.h(-1).g(-1). Such a satisfying activity is due to abundant oxygen vacancy defects bringing about a large number of surface reactive oxygen species and high redox capacity and oxygen migration capacity. It is also because of the synergistic effect of surface OH groups. This strategy will open an exciting avenue to design outstanding catalysts for HCHO removal by defect engineering and the synergistic effect.