<p>Biopolymer-based hydrogels with high mechanical strength have gained great popularity for biomaterials where safety and reliability are highly required. However, most existing biopolymer-based hydrogels are prepared through complicated procedures, usually involving elaborate chemical modification, sophisticated composite technology to combine with reinforcements, and fancy methods to achieve biocompatibility. Here, a facile and effective strategy is demonstrated to fabricate mechanically strong physical hydrogels based on biopolymers without any synthesized polymers or additional reinforcements. The obtained hydrogels are mechanically strong owing to the presence of ionic bonds and coordination bonds as physical crosslinkings. The hydrogel displays regulable mechanical performance within a wide spectrum under various strain rates, and a sandwiched structure with a porous inside architecture. This facile and effective strategy provides a new perspective for the mechanically strong physical hydrogel network construction, which can be further extended to other polymer combinations for physical hydrogels and even chemical hydrogels.</p> Graphical Abstract <p></p>