Antireflection coatings (ARCs) with an indium thin oxide (ITO) layer on silicon heterojunction solar cells (SHJ) have garnered significant attention, which is due to their potential for increasing current density (Jsc) and enhancing reliability. We propose an additional tungsten trioxide (WO3) layer on the ITO/Si structure in this paper in order to raise the Jscand demonstrate the influence on the SHJ solar cell. First, we simulate the Jsccharacteristics for the proposed WO3/ITO/Si structure in order to analyze Jscdepending on the thickness of WO3using an OPAL 2 simulator. As a result, the OPAL 2 simulation shows an increase in Jscof 0.65 mA/cm2after the 19 nm WO3deposition on ITO with a doping concentration of 6.1 × 1020/cm2. We then fabricate the proposed samples and observe an improved efficiency of 0.5% with an increased Jscof 0.75 mA/cm2when using a 20 nm thick WO3layer on the SHJ solar cell. The results indicate that the WO3layer can be a candidate to improve the efficiency of SHJ solar cells with a low fabrication cost.