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Atmospheric water sorption and humidity management are crucial in packaging technologies and logistics industries, because it prevents moisture-induced irreversible damage to products and extends their shelf life during transit. Conventional packing materials lack the capability for active moisture sorption. The development of hygroscopic polymer foams that provide effective barriers against moisture, temperature fluctuations, bacteria and physical shocks is intriguing but remains challenging. Herein, hygroscopic elastic foams (HEFs) are fabricated by integrating all-polymer complexes within multiscale hierarchical pore structures, using straightforward mechanical foaming and ambient drying. During successive cycles of moisture sorption/desorption or compression/release, HEFs afford reversible performance and structural resilience, distinguishing them from most hygroscopic aerogels and hydrogels that are prone to moisture-induced component leakage, structural deformation and performance decay. Atmospheric water sorption spontaneously modulates the toughness, elasticity and durability of HEFs, which are rarely observed in the state-of-the art 3D hygroscopic materials. Additionally, regeneration of wet HEFs can be achieved through low-grade heating. We demonstrated one of the few examples of integrating hygroscopic foams with "self-contained" functionalities tailored for atmospheric water sorption, humidity control and protective packaging, including self-indication, deformation resistance, impact absorption and barriers against various environmental factors (i.e., heat, chemicals and bacteria).