Coiled coils have been one of the major structural motifs in de novo protein design. We have utilized coiled coil designs to develop multi-block proteins that self-assemble into hydrogels with well-defined network topology and specific biofunctional attributes. These fibrillar, telechelic designs consist of a hydrophilic random coil flanked by associating coiled-coil end domains. The amphiphilic coiled-coils preferentially form trimeric bundles that serve as crosslinking agents of the hydrogel and as anchoring elements for attachment to surfaces. The central soluble domain includes peptide ligands with specific binding and signaling functions of extracellular matrix constituents. Circular dichroism and sedimentation equilibrium measurements indicate that the coiled-coil domains of these designs are robust helix formers in a wide range of aqueous solution conditions, with a preference for intermolecular association into trimeric bundles. The triblock proteins self assemble into viscoelastic networks in sufficiently concentrated solutions, which we have studied using dynamic light scattering techniques and computer simulations. Through the use of microscopic and cell proliferation assays, we also show that hydrogels with cell-binding peptide ligands are capable of inducing appropriate cellular responses in cultures of one or more cell types. Such hydrogels have potential applications in tissue engineering and drug control delivery, which are currently being developed.