This paper presents a thick-film microelectromechanical systems thermoelectric sensor fabricated by a low-temperature thermally assisted lift-off process. During the process, thick metal or semiconductor films experience controlled breakup due to thermal reflow of the underlying lithographically defined photoresist patterns, thereby facilitating the sacrificial removal of the photoresist. This enables rapid and reliable patterning of thick films that can otherwise be difficult to achieve by conventional processes. Experimental results with a sensor consisting of a 60-junction thick-film antimony–bismuth thermopile demonstrate an electric conductivity of and a Seebeck coefficient of per junction, which are comparable to those obtained from bulk materials. Thus, the thick-film sensor can potentially allow low-noise, high-efficiency thermoelectric measurements.