Formaldehyde (HCHO), as one kind of human carcinogen, exists in indoor home decoration materials, which is a potential threat to human health. Therefore, the development of a portable gas-sensing technology for high efficiency detection of HCHO is of great worth for human health and environmental monitoring. Herein, the nest-like hierarchical In₂O₃ structures derived from metal-organic framework (MOF) were prepared and the efficient detection of HCHO gas was realized. The sensor generates high response values of 9.47 to 20 ppm HCHO at low temperature of 140 °C. Besides, the sensor shows good response and recovery characteristics, and the response and recovery time 20 s and 40 s, respectively. Moreover, the sensor possesses good reproducibility and selectivity. This work provides a new gas-sensing technology for HCHO detection, which holds important application value for the sensitive detection of formaldehyde in the environment.