Peptide-based nanomaterials with diverse structures and functionalities are considered as typical biomaterials for various applications. Due to their excellent biocompatibility and biological activity, peptide-based nanomaterials have been extensively used in different fields, especially in biomedical community, such as biosensing and bioimaging, cancer therapy, drug delivery, and tissue engineering. Apart from various biomedical applications, self-assembled peptide-based architectures can also be utilized as superior electrode materials for lithium-ion batteries and supercapacitors. In addition, their notable physical and chemical properties endow peptide-based nanomaterials as favorable adsorbents, catalysts, and detectors for both environmental remediation and monitoring. In this chapter, we focus on the design of peptide-based nanomaterials toward energy and environmental science applications.