The application of thermal sprayed WC based cermet coatings is restricted by their structure defects including pores and cracks during thermal spraying. This article fabricated a corrosion-resistant WC-Cr3C2-Ni coating by high velocity oxy-fuel (HVOF) spraying and vacuum sealing with silicone resin. Experiment outcomes show that silicone resin fills into the defects of the WC-Cr3C2-Ni coating. Benefiting from the block of silicone resin in pores and cracks, the sealed coating shows less corrosion pits than the unsealed coating after long-term salt spray corrosion. The sealed coating shows surface without grooves, corrosion pits with smaller size and cracks with decreased amount in comparison with the as-sprayed coating. The vacuum sealing with silicone resin is a strategy with high potential for expanding the application range of thermal sprayed coatings.