Nowadays, more than 45 countries in the world use polymer banknotes in their monetary and banking systems. It is expected that by 2030, another 20 countries will abandon the use of paper banknotes and switch to polymer banknotes. Recent research shows that several countries in the Middle East and the European Union will switch to printing and using polymer banknotes soon due to the advantages of polymer banknotes. Polymer banknotes are made of polymeric materials. They possess very special optical security features and promote sustainability in the world, which motivated us to review recent materials, design, optical technologies, and printing methods in this respect. Since the topic of polymer banknotes is new and there are not many articles and research about them, this review specifically focuses on the structure of the constituent materials and security features and their reuse with an emphasis on sustainability and environmentally friendly banknotes. Specifically, analyses of 3D polymer films and the security properties of polymer banknotes are carried out. Finally, comparison studies with paper banknotes are performed, and pertinent conclusions are outlined.