Practical methods for oceanic uranium extraction have yet to be developed in order to tap into the vast uranium reserve in the ocean as an alternative energy. Here we present a protein hydrogel system containing a network of recently engineered super uranyl binding proteins (SUPs) that is assembled through thiol-maleimide click chemistry under mild conditions. Monodisperse SUP hydrogel microbeads fabricated by a microfluidic device further enable uranyl (UO22+) enrichment from natural seawater with great efficiency (enrichment index, K = 2.5 × 103) and selectivity. Our results demonstrate the feasibility of using protein hydrogels to extract uranium from the ocean.