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Many recently demonstrated devices require the integration of hydrogels and hydrophobic elastomers. Extrusion print is a promising method for rapid prototyping but existing approaches do not fulfill a basic requirement: print integrated structures of a hydrogel and an elastomer, in arbitrary sequence, with strong adhesion. This paper demonstrates an approach to fulfill this requirement. During print, the ink of each material flows through a nozzle under a pressure gradient but retains the shape against gravity and capillarity. During cure, covalent bonds form to link monomer units into polymer chains, crosslink the polymer chains into the polymer networks of the hydrogel and the elastomer, as well as interlink the two polymer networks into an integrated structure. The approach covalently interlinks the hydrogel network and the elastomer network by adding an interlink initiator in one of the inks. An adhesion energy above 5000 J m−2 is demonstrated. Printed morphing structures survive swelling and printed artificial axons survive repeated hits of a hammer. This approach opens a road to the development of soft devices for broad applications in medicine and engineering.

Achieving adhesion between hydrogels and diverse materials in a facile and universal way is challenging. Existing methods rely on special chemical or physical properties of the hydrogel and adherends, which lead to limited applicability and complicated pretreatments. A stitch‐bonding strategy is proposed here by introducing a polymer chain with versatile functional group and triggerable crosslinking property inspired by catechol chemistry. The polymer chain can stitch the hydrogel by forming a network in topological entanglement with the preexisting hydrogel network, and directly bond to the adherend surface by versatile chemical interactions. Through this, the polymer chain solution works as a universal glue for facile adhesion of hydrogels to diverse substrates like metals, glasses, elastomers, plastics, and living tissues, without requiring any chemical design or pretreatment for the hydrogel and adherends. The adhesion energy between polyacrylamide hydrogel and diverse substrates can reach 200–400 J m−2, and it can reach ≈900 J m−2 with a toughened polyacrylic acid polyacrylamide hydrogel. The mechanism of stitch‐bonding strategy is illustrated by studying various influence factors.

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