The extracellular matrix (ECM) is a complex and dynamic three-dimensional (3D) environment consisting largely of a variety of collagenous and non-collagenous fibres, non-fibrous proteins and proteoglycans. Other components often overlooked include various growth factors and other signalling molecules which can diffuse through and bind to various components. The fibrous components of the ECM have a nanoscale architecture to which cells embedded in the ECM, and other biomolecules can attach. Many strategies are being explored to create ECM mimics for tissue engineering applications and as 3D cell-culture environments. These range from fibrous scaffolds composed of synthetic polymers or biopolymers, to fibrous and non-fibrous hydrogel systems. This review will focus on the field of self-assembled nanofibrous hydrogels as ECM mimics and their application to cell and tissue engineering.