Taking inspiration from naturally-occurring proteins, scientists have created protein polymers consisting of functional amino acid sequences that have evolved in nature. The functions of protein polymers can be custom-designed through the modular assembly of protein domains or minimized functional motifs. Elastin-like polypeptides (ELPs) are one of the exquisite building motifs in designing protein polymers. They exhibit stimuli-responsive self-assembling properties, remarkable elasticity, and favorable biological characteristics such as low platelet adhesion and low immunogenicity. With these characteristics, ELP-based materials have been demonstrated to be promising candidates for nanobiomaterial applications such as tissue engineering, drug delivery, and nanobiodevices. This review describes the recent developments in designing modular protein polymers containing ELPs as the building units.