This is the first volume of a two-volume set book, Electromagnetic Wave Innovations for Sustainability, which explores advancements in electromagnetic technologies like photocatalysis and microwave chemistry for sustainable energy production, recycling, and environmental remediation, within the framework of sustainable development goals (SDGs) and the circular economy. It is followed by a second volume, Electromagnetic Wave Innovations for Sustainability II: Recycling and Environmental Remediation. The first volume introduces the fundamental principles that connect sustainability with electromagnetic-wave science. It begins by outlining the concepts of the circular economy, sustainable development, and green chemistry, followed by core theories of electromagnetic waves. Subsequent chapters highlight the role of photocatalysis in pollutant decomposition, wastewater purification, and the advancement of sustainable environmental technologies. The volume concludes with theoretical and industrial perspectives on microwave chemistry, including reactor simulations, extraction technologies, and the contributions of microwaves to sustainable chemical processes.