This chapter integrates sustainability principles into structural optimization, highlighting the role of environmental, economic, and social criteria in engineering decisions. It discusses multi-objective approaches that balance cost, material use, and carbon footprint, alongside traditional structural performance requirements. Techniques for incorporating life-cycle assessment into optimization models are presented, demonstrating how design choices affect long-term sustainability. The chapter explores case studies where optimization supports the development of greener materials and reduced emissions in structural systems. It also examines challenges in integrating sustainability metrics into mathematical formulations. By linking optimization with sustainability goals, the chapter shows how structural engineering contributes to global efforts in resource efficiency and climate impact reduction, equipping readers with tools for responsible and innovative design.