This book offers an extensive summary of recent research on sustainable development in urban planning and architectural design, as presented at the ninth edition of the conference entitled “Urban Planning and Architectural Design for Sustainable Development (UPADSD)” that took place in Florence, Italy, from October 22nd to 24th, 2024. It serves as a forum for professionals, researchers, and individuals interested in urban planning and architectural design to share ideas, information, and experiences. The book is divided into two volumes, with the first volume concentrating on Urban Regeneration: Leveraging Environmental, Cultural, and Social Assets. This book is structured into four sections: Green Infrastructure and Urban Climate Resilience, Urban Design and Mobility Strategies for the Regeneration of Cities and Communities, Urban Heritage and Cultural Identity: Methods and Applications for Conservation, Design Approaches for Community Engagement and Social Sustainability. The second volume is dedicated to Technological Innovations and Emerging Approaches for the Built Environment and Smart Cities, comprising four sections: Innovative Building Materials and Techniques, Energy Efficiency and Climate Solutions in the Built Environment, Advanced Tools and Methods for Urban Analysis, Evaluation, and Decision-Making, Digital Transformation and Smart Cities. Envisioning the Urban Future.