We demonstrate a wearable temperature sensor based on a Peltier thermoelectric device. The wearable temperature sensor is attached to the wrist using a bracelet, which can monitor, control, and change the human body temperature using a local temperature change. The body temperature was changed by transferring the heat from one side to the other side of the Peltier semiconductor or vice versa. The feedback control system was used to maintain the human body temperature during increases and decreases in the temperature of the surrounding environment. The results showed the changes in body temperature over 300 s in 100 trials with different rates of increase and decrease in the temperature. The highest relative increase in temperature was 86.1% with a change from 18.7 to 34.8 °C, while the lowest relative increase was 1.2% with a change from 24.6 to 24.9 °C. The average change was 33.5% with a standard deviation of 25.5%. This technology provides a basis for next-generation wearable temperature sensors to control and change the temperature of the human body.