Abstract: Atomic layer deposition (ALD) represents a high-precision thin film deposition technique, distinguished by its sub-nanometer thickness control, superior uniformity, and unique three-dimensional conformality. These attributes facilitate uniform film growth on complex nanostructures and high-aspect-ratio surfaces. As gas sensor technology progresses, ALD has shown extensive application potential in the preparation and modification of gas-sensing materials. Particularly in the preparation of thin films, nanostructures, heterojunctions, and nanoparticle-loaded structures, ALD technology has shown outstanding performance. By enabling atomic-level control of film thickness and composition, ALD substantially enhances the sensing performance. This review highlights recent significant advancements in the use of ALD technology for gas sensors and examines the current research challenges and future prospects of ALD within this domain.