Two-dimensional semiconductors are identified by the international roadmap for devices and systems as key candidate materials for future sub-nm nodes, owing to their atomic-scale thickness, smooth surface without dangling bonds and capability to suppress short-channel effects. Focusing on the current status of the full-chain development of two-dimensional semiconductors from basic materials science to system-level integration, the intrinsic physical advantages over traditional silicon-based materials and the progress in preparation processes were systematically analyzed. The latest progress and technical bottlenecks of core process modules including contact resistance engineering, gate dielectric integration and device architecture evolution of two-dimensional semiconductor transistors were reviewed in detail. Meanwhile, the development trajectory from early single-transistor verification to large-scale integrated circuits was traced comprehensively, and the collaborative challenges among materials, processes and design during the integration process were analyzed. The unique potential of two-dimensional semiconductors in emerging paradigms such as in-memory sensing and computing, neuromorphic computing and van der Waals heterogeneous integration is further discussed.