Realisation of integrated, low-cost, and efficient solutions for high-speed, on-chip communication requires terahertz waveguides and holds tremendous potential in future information and communication technologies, including terahertz wireless communication, terahertz integrated circuits, and terahertz interconnects for intra-/inter-chip communication. However, conventional approaches to terahertz waveguiding suffer from sensitivity to defects and considerable bending losses at sharp bends. Here, building on the topological phase of light, we experimentally demonstrate robust terahertz topological valley transport on low-loss, all-silicon chip. The valley kink states are excellent information carriers due to their robustness, single-mode propagation, and linear dispersion. By leveraging on such states, we demonstrate error-free communication through a highly-twisted domain wall at an unprecedented data rate (> 10 Gbit/s) that enables real-time transmission of uncompressed 4K high-definition video. Our work provides the first experimental demonstration of the topological phases of terahertz wave, which would inspire rich research on varied topological phases with terahertz applications.