4th IEEE International Conference on Knowledge Innovation and Invention 2021 (IEEE ICKII 2021) will be held in Taichung, Taiwan on July 23-25, 2021, and it will provide a unified communication platform for researchers in the topics of information technology, innovation design, communication science & engineering, industrial design, creative design, applied mathematics, computer science, electrical & electronic engineering, mechanical & automation engineering, green technology & architecture engineering, material science and other related fields. Professional practice in the information, innovation, communication, and engineering fields are welcome to participate in IEEE ICKII 2021. This conference enables interdisciplinary collaboration of science and engineering technologists in the academic and industrial fields, as well as networking internationally. During the conference, there will be substantial time for presentation and discussion. Attendants will find various activities useful in bringing together a diverse group of engineers and technologists across the disciplines for the generation of new ideas, collaboration potential and business opportunities.