A method for binding a tough double-network (DN) hydrogel and a porous solid utilizing the double-network principle is proposed. The effects of the pore size of the solid and the structure of the DN gel in the pores on bonding strength were investigated by a peeling test. Porous solids with pore sizes of the order of several microns afforded strong gel–substrate interfaces. Under optimal conditions a bonding strength as high as ∼1000 N m−1 was reached. The results obtained were compared with the strength of the bulk DN gel, and discussed in terms of the double-network principle at the bonding interface.