Atmospheric water harvesting (AWH) provides a sustainable solution for decentralized freshwater production by utilizing the abundant yet overlooked moisture in the atmosphere. Recent advances in AWH have been driven by two major approaches: bioinspired surface fog capture, involves droplet capture, growth, coalescence, and transport, and sorption-based materials enabling moisture uptake and release, particularly suited for arid and semi-arid regions. This review presents a unified framework that systematically integrates working mechanisms, material design principles, and system-level considerations across the two AWH pathways. Representative advances in microstructure, wettability control, pore size regulation, and adsorption isotherms are discussed in relation to their impacts on AWH capacity and the environment-dependent selection of appropriate AWH systems. Additionally, this review highlights the extension of AWH toward multifunctional applications of AWH, including passive cooling, electricity generation, humidity regulation, and agricultural irrigation. Despite significant progress, key challenges remain in limited yields, system mass transfer and thermal management, scalable operational stability, particularly under fluctuating conditions. Finally, future research directions are outlined to guide the continued evolution of AWH technologies toward practical deployment, spanning advanced materials engineering, interdisciplinary multifunctional integration, system-level energy efficiency, and long-term stability. Overall, this review presents a comprehensive framework for the rational multiscale design of next-generation AWH materials and systems, establishing a solid scientific foundation for reliable, high-performance technologies to mitigate global water scarcity challenges.