Self-assembling biomaterials offer an unprecedented chance of successfully facing most of the challenges of various biomedical fields, and, in particular, of tissue engineering. Nonetheless co-assembling peptides (CAPs), taking advantage of the theory and empirical findings developed for self-assembling peptides, could provide an even better control over cell cultures, drug delivery, and transplantation therapies. This study follows a "full" bottom-up approach to develop new CAPs for neural tissue engineering applications. After molecular aggregation analysis via coarse-grained simulations, LKLK12, LDLD12, and the functionalized KLPGWSG-LDLD12 CAPs are synthesized and characterized assessing their co-assembled secondary structures, the biomechanical properties of the obtained hydrogels, and the morphological features of the assembled nanofibers. The biological influence on viability and differentiation of human and murine neural stem cells are tested in vitro and neuroregenerative potentials in complete spinal cord transections are verified in vivo. Upon mixing of CAPs, the spontaneous formation of double layers of beta-sheets with a high degree of integration of the two CAP species is demonstrated. The formation of entangled nanofibrous structures give rise to shear-thinning hydrogels. The in vitro results are comparable to a standard state-of-the-art cell culture substrate and nervous regeneration in vivo is enhanced.