A new machining method, cryogenic-ultrasonic vibration-assisted milling (CUVAM), is proposed to improve the workability of Inconel 718. This study examined the machining mechanism of CUVAM technology at different machining parameters. The cutting force, chip, tool life, workpiece surface morphology, and surface integrity after conventional machining (CM), cryogenic cooling machining (CCM), and CUVAM were compared. The experimental data showed that cryogenic assistance could effectively improve the machining environment and coefficient of friction (CoF) and improve surface integrity. On the other hand, the cutting force increases after CCM due to the low-temperature brittleness of Inconel 718, but the ultrasonic vibration assistance in CUVAM can suppress the increase in cutting force. CUVAM well combines the advantages of cryogenic assistance and ultrasonic assistance. Compared to CM, the CUVAM method can reduce the cutting force by 36.5% and have a beneficial impact on tool life. The chipping effect was more obvious. Compared to CCM, the surface roughness after CUVAM was reduced by 39.1%. The excellent machinability of the CUVAM method was verified through the combination of experiments and theory, which provides a new method for the high-quality, high-efficiency, and pollution-free machining of Inconel 718.