In this article, we exploit electromagnetic-circuit co-design approach to demonstrate a digitally reconfigurable metasurface at 0.3 THz. Realized on an industry standard 65-nm CMOS process, each metasurface CMOS chip consists 12×12 array of reconfigurable split-ring unit cells. Reconfiguration of each unit cell happens through EM-circuit co-designed CMOS transistor switches. Each unit-cell is individually addressable and controllable with on-chip high-speed digital back-end. Scalability of this approach is demonstrated by tiling such CMOS chips to form a larger aperture of 2×2 array. We experimentally demonstrate multi-functional applications namely, arbitrary amplitude and phase control, high-speed beam modulation with switching ON/OFF ratio of ~25 dB at a maximum clock speed of 5 GHz, beamforming capability of ± 30°, and spatial wavefront manipulation using binary-amplitude-only holography technique at 0.3 THz. Each metasurface consumes a total DC power of (240 μW) consumption and operates at 1.2V.