<p>Hardened steels, characterized by high hardness, high strength, and wear resistance, are widely used in the manufacturing of gears, bearings, molds, and cutting tools. However, their elevated hardness leads to the challenges such as excessive cutting forces and severe tool wear during machining. Energy field-assisted machining, which enhances machinability by modifying the materials removal mechanisms or altering the materials properties, offers an effective solution to these difficulties. This paper provides a comprehensive review of recent advances in the energy field-assisted machining of hardened steels, including ultrasonic-assisted machining, laser-assisted machining, and electropulsing-assisted machining. The mechanisms and process innovations associated with these methods were systematically summarized and analyzed. The limitations of current research and future development directions were also highlighted. The findings are expected to facilitate the advancement and industrial application of the machining technology of hardened steels.</p>