Two complementary β-sheet-forming decapeptides have been created that form binary self-repairing hydrogels upon combination of the respective free-flowing peptide solutions at pH 7 and <0.2 wt %. The component peptides showed little structure separately but formed extended β-sheet fibres upon mixing, which became entangled to produce stiff hydrogels. Microscopy revealed two major structures; thin fibrils with a twisted or helical appearance and with widths comparable to the predicted lengths of the peptides within a β-sheet, and thicker, longer, interwoven fibres that appear to comprise laterally-packed fibrils. A range of gel stiffnesses (G’ from 0.05 to 100 kPa) could be attained in this system by altering the assembly conditions, stiffnesses that covered the rheological properties desirable for cell culture scaffolds. Doping in a RGD-tagged component peptide at 5 mol % improved 3T3 fibroblast attachment and viability compared to hydrogel fibres without RGD functionalisation.