It is beneficial to have sensors capable of harvesting photoenergy in the era of Internet of Things (IoT) and 5 G integrated infrastructure. In this paper, we report the piezo-optoelectronic coupling characteristic of n-type 3C‐SiC/n‐type Si heterostructure and demonstrate it with a mechanical strain sensing device capable of harvesting photoenergy. The device is capable of generating a photovoltage as high as 3.4 mV when illuminated by a laser power as small as 10 μW, i.e. four times higher than similar sensors in previous studies. In addition, the strain sensitivity ΔV/V/ε ratios are 9.94 and 13.11 for tensile and compressive strain, respectively, which are five times better than conventional metal strain gauges. These findings contribute to the overall understanding of the piezo-optoelectronic coupling effect of SiC/Si heterojunction paving the way for the development of multifunctional sensors with light harvesting capabilities.