Because of their unique properties, magnetic nanosheets have attracted extensive attention in magnetic resonance imaging, microwave absorption, catalysts, batteries, adsorption purification, and other fields. In this paper, the preparation methods and functional application direction of magnetic nanosheets were summarized. The effects of different preparation methods on the morphology, size, and thickness of magnetic nanosheets were described, the synthesis mechanism and performance control factor were summarized to provide theoretical support for their large-scale preparation. In addition, the functional application progress of magnetic nanosheets in various fields was emphatically introduced. The significance of basic properties and the functional modification of magnetic nanosheets for further application were summarized. Finally, the problems to be solved urgently in the research of magnetic nanosheets and the future research direction were prospected.