Lanthanide-based perovskite oxide semiconductors have garnered significant attention due to their exceptional electrical and sensing properties, making them promising candidates for gas sensing applications. This review paper focuses on developments and the impact of doping in lanthanide-based perovskite oxide semiconductors for gas sensing purposes. The review explores the factors influencing gas sensing performance, such as operating temperature, dopant selection, and target gas species. The role of dopants in enhancing gas sensing selectivity, sensitivity, response/recovery times, and stability is discussed in detail. Comparisons are drawn between doped perovskite oxide semiconductors, undoped counterparts, and other gas-sensing materials. Practical applications of lanthanide-based perovskite oxide semiconductor gas sensors are outlined, including environmental monitoring, industrial process control, and healthcare. The review also identifies current challenges and future perspectives in the field, such as the exploration of novel doping strategies and integration with emerging technologies like the Internet of Things (IoT). The findings emphasize the potential of these materials in advancing gas sensing technology and the importance of continued research in this field.