In situ injectable hydrogels have shown tremendous potential application in the biomedical field due to their significant drug accumulation at lesion sites, sustained release and markedly reduced systemic side effects. Specifically, peptide-based hydrogels, with unique biodegradation, biocompatibility, and bioactivity, are attractive molecular skeletons. In addition, peptides play a prominent role in normal metabolism, mimicking the natural tissue microenvironment and responding to stimuli in the lesion environment. Their advantages endow peptide-based hydrogels with great potential for application as biomedical materials. In this review, the fabrication and production of peptide-based hydrogels are presented. Several promising candidates, which are smart and environment-sensitive, are briefly reviewed. Then, the recent developments of these hydrogels for biomedical applications in tissue engineering, as drug/gene vehicles, and anti-bacterial agents are discussed. Finally, the development of peptide-based injectable hydrogels for biomedical applications in the future is surveyed.