Self-assembling peptides have gained increasing attention as versatile molecules to generate diverse supramolecular structures with tunable functionality. Because of the possibility to integrate a wide range of functional domains into self-assembling peptides including cell attachment sequences, signaling domains, vaccine epitopes, and even therapeutic moieties, complex nanostructures can be obtained with a wide range of applications in the biomedical field. The first part of this Review provides a concise overview of how peptide primary and secondary structure dictate the way such self-assembling peptides organize into higher ordered, supramolecular structures. Next, an overview of the literature will be given on recent studies on peptide self-assembly for application in drug delivery, vaccination, and tissue engineering.