The present disclosure discloses a temperature sensor, a display panel, and a display apparatus, in the field of sensors. The temperature sensor includes a ring oscillator consisting of n levels of phase inverters, where n is an odd number greater than or equal to 1. Each level of phase inverter includes a first thin film transistor (TFT) and a second TFT that are connected in series. An on/off state of the second TFT is configured to be in a normally-on state, an on/off state of the first TFT is configured to be determined by a signal input to the phase inverter, and mobility of an active layer material of the first TFT is greater than mobility of an active layer material of the second TFT.