Flexible metal-air batteries (MABs) hold promises for powering wearable electronics due to exceptional theoretical energy density, affordability, and deformability. Recent advancements in MAB design, materials (electrode and electrolyte), and fabrication have enhanced electrochemical performance. However, achieving the trifecta of superior mechanical flexibility, safety, and user comfort remains a challenge. Focusing on Zn-air and Li-air examples, this chapter explores progress in flexible MABs, including configurations, flexible metal anode design for enhanced cyclability under deformation, gel polymer electrolytes for efficient ionic transport and stability, and air cathode optimization for catalytic activity and oxygen transport. Key challenges and promising future directions for seamless integration of MABs into next-generation wearable electronics are discussed.