Triethylamine is extremely harmful to human health, and chronic inhalation can lead to respiratory and hematological diseases and eye lesions. Hence, it is essential to develop a triethylamine gas-sensing technology with high response, selectivity, and stability for use in healthcare and environmental monitoring. In this work, a simple and low-cost sensor based on the Pt-and Ce-modified In2O3 hollow structure to selectively detect triethylamine is developed. The experimental results reveal that the sensor based on 1% Pt/Ce12In exhibits excellent triethylamine-sensing performance, including its insusceptibility to water, reduced operating temperature, enhanced response, and superior long-term stability. This work suggests that the enhancement of sensing performance toward triethylamine can be attributed to the high relative contents of OV and OC, large specific surface area, catalytic effect, the electronic sensitization of Pt, and the reversible redox cycle properties of Ce. This sensor represents a unique and highly sensitive means to detect triethylamine, which shows great promise for potential applications in food safety inspection and environmental monitoring.