Self-assembling short peptides are very attractive building blocks for soft materials such as hydrogels that do not persist in the environment and could find a wide variety of applications, spanning from medicine to environmental remediation. In particular, hydrogels composed of simple peptides made of 2-3 amino acids are highly sought after for their ease of preparation, simple scale-up, and low cost.[2] However, the resulting materials often have limited mechanical and physical properties. For this reason, research is very active towards the development of nanocomposites whereby the presence of nanofillers could provide further advantages, such as increased resistance against applied stress, and higher stiffness. To this end, carbon nanostructures bear great potential, not only for their outstanding physico-chemical properties, such as high resilience and low density, but also for the possibility to introduce additional properties. For instance, carbon nanotubes (CNTs) can increase the gel conductivity and boost the biochemical activity of conductive tissues, such as the nerve and cardiac, for regenerative medicine. They can serve as fluorescent probes for sensing. Graphene and its derivatives have been used as carriers for bioactives, and to impart near-infrared light responsiveness. Carbon dots can impart luminescence to peptide gels, and peptides can modulate their fluorescence. In our labs, we have found that the nanocarbon type can have important consequences on peptide selfassembling ability. In particular, the anisotropic morphology of carbon nanotubes (CNTs), was found to be ideal to yield a hybrid matrix with peptide fibrils, providing hydrogels with a remarkable increase in stiffness, especially in the case of double-walled CNTs. Besides, also quasi-spherical carbon nanoonions (CNOs), which are concentric fullerene nanoparticles, could improve the stiffness of the peptide gels, although to a lower extent. Importantly, oxidized CNOs were found to non-covalently interact with the self-assembling peptide molecules, without interfering with their ability to stack and fibrillate for gelation, whilst effectively inhibiting fibrils' bundling into fibers. As a result, in the presence of oxidized CNOs, peptide self-assembly yielded a gelling network of thinner fibrils that were better interconnected, thus more resistant against gel rupture due to applied stress. Furthermore, the nanocomposites displayed promising cytocompatibility in vitro on cell cultures.