Therapeutic peptides have emerged as a powerful class of bioactive molecules with significant potential in the treatment of a wide range of diseases. Unlike traditional small molecules and monoclonal antibodies, peptides offer unique advantages such as a smaller size, enhanced tissue penetration, and easier chemical modification, while still maintaining high specificity and selectivity for a wide range of molecular targets. This chapter explores the key properties and mechanisms of action of therapeutic peptides, highlighting their role in modern pharmacology. It delves into the challenges associated with their development, such as stability, bioavailability, and immunogenicity, while also examining the latest advances in peptide synthesis and design. Additionally, the chapter showcases the therapeutic applications of peptides in the treatment of autoimmune diseases, cancer, diabetes, neurodegenerative disorders, and more. By examining the latest technological innovations, including nanotechnology and artificial intelligence, this work discusses the future opportunities and challenges in advancing peptide-based therapies. Ultimately, this chapter emphasizes the transformative potential of therapeutic peptides in the field of medicine, offering a glimpse into the next generation of targeted, personalized therapies.