This two-volume set CCIS 2612-2613 constitutes the refereed proceedings of the Second International Conference on Renewable Energy, Green Computing, and Sustainable Development, REGS 2025, held in Hyderabad, India, during February 21–22, 2025. The 54 full papers were carefully reviewed and selected from 351 submissions. REGS 2025 is an interdisciplinary conference that aims at diverse fields of engineering and technology with a focus on smart and energy efficient computing, green technology and sustainable systems design and development, ranging from theoretical developments to industrial problems.