Pressure sensing is a critical task of microelectromechanical systems with a wide range of applications. Enhancing the performance such as sensitivity, durability, reliability, linearity and response time of pressure sensors has always been a top priority for researchers and technology developers. This paper demonstrates a new method for enhancing the performance of a piezoresistive pressure sensor. By using light illumination combined with controlling supply current, the performance of a 3C-SiC/Si heterojunction piezoresistive pressure sensor is significantly improved. The sensitivity of the pressure sensor is enhanced a few hundred thousand times under bright condition in comparison with that under dark condition. This enhancement is unprecedented for a micromachined pressure sensor. In addition, the durability, signal to noise ratio and measurement range are substantially improved.