Gallium Nitride (GaN), as a representative of wide bandgap semiconductors, has become a focus of semiconductor research in recent years due to its excellent electronic and optoelectronic properties. Meanwhile, twodimensional GaN, with its distinctive layered structure and tunable bandgap, has garnered significant attention in domains such as power electronics, optoelectronics, energy conversion and flexible wearable devices. Over the last few years, substantial research has been conducted on the fabrication of two-dimensional GaN materials and their device applications. Despite the broad prospects for the preparation and application of 2D GaN, it continues to face several challenges. This review highlights methods for the preparation of two-dimensional gallium nitride materials and device applications for power electronics, optoelectronics, as well as communications, detectors, and sensors. It summarizes different synthetic routes based on nitridation reactions, graphene-assisted heteroepitaxial growth, etc., and exemplifies the current status of device application research based on 2D GaN materials. Additionally, it anticipates the challenges encountered by current research and the emerging trends in future development, with the aim of facilitating the practical implementation process of 2D GaN.