© 2019 IEEE. Magnetic sensing with preserved performance at high temperatures over 773 K has been difficult for the traditional sensing techniques. Here, we propose and demonstrate a novel high-temperature magnetic sensor based on the hybrid structure of Galfenol/Ti/single crystal diamond (SCD) MEMS resonators to circumvent the challenges in magnetic sensing. It is observed that the magnetic sensitivity is improved at elevated operation temperatures. The developed magnetic sensor exhibits a stable high-sensitivity and low noise level ~247 pT/√Hz at 773 K, which exceeds those of reported magnetic sensors. The concept of FeGa/Ti/SCD MEMS offers a promising strategy for developing high-temperature magnetic sensors with full merits super to the existing ones.