Natural load-bearing soft tissues exhibit amazing properties that are difficult to replicate with synthetic materials. Their unique combination of high water content, stiffness, strength, toughness and deformability is possible due to sophisticated and reconfigurable networks of stiff collagen nanofibers and soft biomacromolecules. Here we present water-rich biomimetic composites that emulate the collagen-proteoglycan network in soft tissues at multiscale levels. The hydrogen bonding between stiff aramid nanofibers and soft poly(vinyl alcohol) afford synergistic stiffening and toughening, allowing the nanofiber network to self-organizes under stress for effective load bearing and energy dissipation. They exhibit mechanical properties parallel or superior to those of load-bearing soft tissues, e.g., articular cartilage, forming the foundation for development of a new class of load-bearing biomaterials.