Adhering soft hydrogels to hard substrates is challenging. Existing adhesion approaches mainly rely oninterfacial chemical bonds or physical interactions, which typically require complex fabrication processesor specific surface properties. Herein, we report a convenient approach to achieving effective hydrogeladhesion onto various hard substrates with in-situ formed crystalline zones by heating. Semicrystallizablepoly(vinyl alcohol) hydrogels were directly cast on various subtracts by a dryingswellingprocess, which demonstrates strong adhesion with adhesion energy as high as 890 J/m2. Theadhesion performance demonstrates an obvious positive correlation with the crystalline property. Therefore, the factors determining the crystalline degree, including the polymer type and preparationtemperature, demonstrate remarkable influences on the adhesion performance. Moreover, this adhesionperformance manifests high durability in harsh environments. Benefitting from the strong and durableadhesion performance, the crystalline gels can serve as a tie coating layer to joint various hydrogels,which demonstrate satisfactory antifouling ability. Therefore, this strategy may endow the materials withgreat potential for various practical applications in the future.