This paper presents for the first time the design, fabrication, and demonstration of a dielectric waveguide (DWG)-based ortho-mode sub-THz interconnect channel for planar chip-to-chip communications. By combining the proposed new transition of microstrip line with DWG orthogonally, the ortho-mode transition is constructed to form an ortho-mode channel. The measured minimum insertion losses for the Ey11 mode and the Ex11 mode are 6.6 dB with 20.3-GHz 3-dB bandwidth and 6.5 dB with 55.2-GHz 3-dB bandwidth, respectively. The simulation and measurement results agree well with each other.