Protein gels with controlled viscoelastic properties could find numerous material and biomedical applications. Feather keratin is naturally abundant protein while its gelation property has not been explored. In this study hydrogel from fully reduced feather keratin was prepared by dialysis. The objectives of this work were to study the molecular mechanism of self-assembly of feather keratin gel and to characterize the structural and viscoelastic properties of hydrogels prepared under various pHs (3–9) and temperatures (50–90 °C). Re-oxidation of free cysteine thiols and formation of hydrophobic interactions and hydrogen bond were determined as the main stabilizing forces in self-assembly of feather keratin gel. Adding thiol blocking agent of N-ethylmaleimide leads to reduced storage modulus of keratin gel; gelation was completely inhibited at 82% blockage of free thiols. Increasing temperature decreased storage modulus, while gelation at pH 3 resulted in stiffer gels compared to pHs of 5, 7 and 9. Feather keratin gels with tunable viscoelastic properties could find applications as engineered scaffolds for different tissues.