This review discusses the latest advancements in Ultrasonic-Assisted Directed Energy Deposition (UA-DED) for metal additive manufacturing (AM). Directed Energy Deposition (DED) is a promising AM technique for fabricating large metal components, but it faces challenges such as residual stresses, distortion, porosity, and surface roughness due to rapid melting and solidification. UA-DED integrates ultrasonic vibrations to address these issues. The review critically examines the current state of UA-DED, focusing on its working principles, system components, and material improvements. It also explores the optimization of process parameters and the interaction mechanisms between ultrasonic and DED processes. The review highlights the potential of UA-DED to enhance microstructure, reduce porosity, and improve mechanical properties. It discusses the challenges of UA-DED, including the complexity of ultrasonic parameters and the need for further research. The review concludes with perspectives on future developments in UA-DED, emphasizing its potential for high-precision and high-performance applications in various industries.This review discusses the latest advancements in Ultrasonic-Assisted Directed Energy Deposition (UA-DED) for metal additive manufacturing (AM). Directed Energy Deposition (DED) is a promising AM technique for fabricating large metal components, but it faces challenges such as residual stresses, distortion, porosity, and surface roughness due to rapid melting and solidification. UA-DED integrates ultrasonic vibrations to address these issues. The review critically examines the current state of UA-DED, focusing on its working principles, system components, and material improvements. It also explores the optimization of process parameters and the interaction mechanisms between ultrasonic and DED processes. The review highlights the potential of UA-DED to enhance microstructure, reduce porosity, and improve mechanical properties. It discusses the challenges of UA-DED, including the complexity of ultrasonic parameters and the need for further research. The review concludes with perspectives on future developments in UA-DED, emphasizing its potential for high-precision and high-performance applications in various industries.