Temperature measurement on the nanoscale is important for applications such as detecting the local temperature changes associated with microelectronics, optics, microfluidics, chemical reaction and biochemical processes, such as living cells and nanomedicine. The drive for information at this scale comes from the electronics industry, materials development and the biosector, combined with rapid development in enabling technologies such as sensor integration and manufacture. The scale of the application and the nature of physical probes distorting the local temperature field due to thermal conduction effects, or optical probes due to thermal radiation heat transfer or energy associated with excitation of a medium, means that great care needs to be taken in order to provide meaningful measurements. This chapter provides an overview of temperature measurement principles along with a review of some of the principal and emerging technologies for nanoscale temperature measurement.