Recently, the intelligent, smart gas sensing devices have shown great prospects in applications of gas component recognition and concentration detection, which largely depends on the precise structures and compositions of sensing layers. Various synthetic strategies are promising for the scalable production and performance optimization of the sensing materials. In this review, different gas sensing materials with controlled preparation such as wet-chemical synthesis, electrospinning method, vapor-phase synthesis and exfoliation routes are summarized. Then, the representative design strategies and gas sensing performances in gas sensors are also discussed. Finally, the recent progress of some gas sensing devices is presented, with the emphasis on their device structure, circuit design, and applications. It is believed that this review will provide some guidelines for designing novel gas sensing materials with controllable synthetic methods and sensing behaviors for advanced gas sensors.