Selective detection of carbon monoxide (CO) at trace (ppm) levels with high sensitivity is of great interest for reducing human health risks, especially among workers in indoor industrial settings. Although existing chemiresistive CO gas sensors perform well at high temperatures, room-temperature (25 ± 2 °C) CO gas sensors face significant challenges due to limited molecular interactions between CO and traditional sensing materials, such as metal oxides, polymers, and carbon-based compounds, leading to poor gas sensitivity. To alleviate these problems, this research explores V2CTx MXene, synthesized via aluminum etching from V2AlC using hydrofluoric acid (HF), followed by TMAOH intercalation, which exhibits high electrical conductivity, excellent chemical stability, large surface area, and strong mechanical durability. After that, a chemiresistor is fabricated by drop-coating V2CTx MXene onto gold interdigitated electrodes, exhibiting improved room-temperature (25 ± 2 °C) CO gas detection with a response of 24.59% to a 10 ppm CO exposure, and response and recovery times of 246 s and 354 s, respectively. Additionally, the sensor exhibited high selectivity for CO gas over reducing and oxidizing gases, good reversible behavior, consistent repeatability, long-term stability, and a detection limit of 1 ppm. These excellent gas-sensing properties can be attributed to the surface functionalities (-O, -OH, -F, -Cl), exceptional electrical properties of V2CTx MXene, and the Schottky contact between V2CTx MXene and Au electrode, revealing that V2CTx MXene is a promising candidate for CO gas monitoring in various applications including indoor air quality monitoring, industrial environments, human health and vehicle emissions on roadways.