We are pleased to present the selection of contributions from the 2023 7th International Conference on Materials Sciences and Nanomaterials (ICMSN 2023) which was held in Cambridge, United Kingdom, during July 11-13, 2023, and the 2023 6th International Conference on Advanced Composite Materials (ICACM 2023) which was held in Hosei University, Tokyo, Japan, during August 23-25, 2023. These contributions from the ICMSN 2023 and ICACM 2023 included submissions from universities, research institutes and industries. All of the papers were peer-reviewed by the conference committee members and international reviewers. They were selected based on their quality and relevance to the subjects of the conferences. The fields of this selection included structural materials, nanomaterials, electronic materials, material chemistry, polymers and composites, mechanics of composite materials, materials processing engineering, and so on.