A circular economy (CE) is a regenerative system in which resource input and waste, emission, and energy leakage are minimized by closing, and narrowing material and energy loops. To facilitate the development and implementation of a CE system, the “2021 The 5th International Conference on Integrated and Innovative Solutions for Circular Economy” is organized by the CTCI Education Foundation, Taiwan Institute for Sustainable Energy (TAISE), National Cheng Kung University, and National Taiwan University. The purpose of this conference is intended to foster the exchange and dissemination of state-of-the-art technical information among researchers, educators, and practitioners. The technical sessions in the conference will be divided into 3 sessions (1) Session A: Sustainable Consumption and Production (2) Session B: Carbon Neutrality, and (3) Session C: Municipal and Construction Wastes to Energy and Resources. The themes to be discussed in the conference are as follows: