Customized assembly of nanomaterials into three-dimensional macroscopic objects may offer versatile functional nanostructures. Gelation is a common route to this end, but unstable assembly of typical one-dimensional nanomaterials arising from their non-flat geometry of weakly interacting building blocks has remained a significant challenge. We report versatile reliable open nanoporous graphene nanoribbon hydrogel formation via straightforward interfacial layer-by-layer self-assembly. Atomically flat surface of graphene nanoribbon enables a stable gelation, overcoming the geometrical penalty of one-dimensional building blocks. The resultant hydrogel readily provides compact open porous web-like gel framework along with a wide range of controllability in the engineering of surface functionality, composite preparation and three-dimensional customized morphology formation. Large surface area and open porosity of the synergistic hydrogel structure simultaneously attain fast responsivity and high sensitivity in enzymatic biosensor application as well as fast rate capability and high capacitance in supercapacitor application.