Ag 2 Se is an n-type room temperature thermoelectric material with excellent intrinsic thermoelectric and mechanical properties and has received increasing attention from researchers in recent years. In this study, we have developed an ultrafast sintering method to prepare Ag 2 Se bulk materials combining the cold pressing process and the Joule-heating method, which can be completed in less than one minute. By modifying the sintering temperature, the electrical transport properties of the Ag 2 Se samples can be tuned. The ultrafast sintering process maintains the porous structure of the cold pressed samples, resulting in a significantly reduced thermal conductivity as low as 0.56 W/(m · K) at 300 K, which is ~44% lower than that of the Ag 2 Se bulk prepared by using the spark plasma sintering method. Eventually, a room-temperature zT value of ~0.66 is obtained in ultrafastsintered Ag 2 Se at 673 K, which is comparable to the room-temperature thermoelectric materials prepared by conventional methods. This work proposes a convenient and efficient method for sintering thermoelectric materials with promising thermoelectric performance.