Mankind has often taken inspiration from the nature to solve problems since nature has sophisticated processes, refined for thousands of years. While manmade systems are unsustainable, natural processes embody sustainability principles; therefore, there are many things to learn from nature in order to solve design problems and create a more sustainable future. This is the promise of a biomimetic design approach. Another design approach is biodesign, and it also involves utilizing natural elements inside the design. The building façade is a problematic research area since it is at the intersection between living spaces and natural environment; thus it faces many problems especially regarding energy-air-water transition between indoors and outdoors. Application of key sustainability concepts in architecture such as energy requirements, form and structure, and sustainability considerations can be enhanced by learning from natural processes. This chapter looks at cutting-edge design principles, materials, and designs in building façades through the lens of biomimetics and biodesign. First, the design principles and then the materials and some cases are explained. The concepts of biomimicry and biodesign are in harmony with the concept of sustainability; however, to reach sustainable façade solutions, the sustainability principles should be at the core of the design problem definition.