A significant step toward commercialization of novel carbon nanotube (CNT) electronics involves the development of large area and high-throughput processes for the fabrication of high-quality CNT films. In this study, we report CNT-based gas sensors with exceptionally high as well as rapid response to various test gases. Highly uniform CNT thin films, prepared using a reliable and reproducible low-cost spray deposition process, are utilized as resistive networks for gas detection. Sensors show a clear and immediate change in resistance as a response to test gas exposure. The high uniformity and low density of the CNT films employed in our chemiresistor provide the means for achieving exceptional response under ambient conditions without any further functionalization, rendering them promising for adoption into a wide range of applications, especially where low-cost room-temperature operation is desired. In an attempt to further reduce production cost, we demonstrate the first implementation of a fully sprayed full-CNT gas sensor on low-cost substrates yielding reasonable device performance.