Gas-sensing materials have seen significant development since the discovery of chemiresistive sensors, but the impact of electrode material and interdigitated electrode structure (IDEs) geometry on sensing performance has yet to be fully explored. To address, this study aims to investigate the effect of finger width (Wf) in IDEs on gas-sensing response. Tungsten oxide (WO3) is chosen as a sensing material to detect NO2 gas, synthesized using a simple hydrothermal method, and its material characteristics are corroborated using various analytical techniques. Next, three chemiresistive sensors with different Wf values of 50 µm (S1), 100 µm (S2), and 200 µm (S3) were fabricated. Gas-sensing properties show that S1 had a response 2.79 times higher than S2 and 3.28 times higher than S3. Accordingly, S1 is used to evaluate other sensing parameters. These parameters exhibit at least 1.61 times higher sensing response to NO2 than other gases, which might be attributed to the higher adsorption energy of NO2 on the WO3 surface. Furthermore, S1 provided a minimum detection limit of 450 ppb, quick response time and recovery time, and good repeatable response. These sensing properties ensure that the sensor has great potential for monitoring NO2 gas in various applications.