Frost is undesirable in many applications. Previous methods of defrosting are either energy intensive or ineffective in the long term. Meanwhile, frost is a valuable freshwater source whose production is delayed due to the solid state and lengthy accumulation of frost. Here, a salt-solution-infused thin-film condenser (SSTFC) is proposed for anti-frost at low energy consumption and simultaneous freshwater production. The SSTFC is composed of a highly permeable lower layer for salt solution infusion and an ultrathin hydrophobic top layer for constraining the infused solution and incorporating condensed vapor into the underlying solution at various low temperatures. The gradually diluted salt solution can be passively transported for regeneration and freshwater production by solar energy. The regenerated salt solution can be pumped back to the SSTFC for continuous operation of the system. Energy consumption can be saved by >50% compared to conventional methods.