This book constitutes the refereed post-conference proceedings of the 12th International Conference on Mobile Communication and Healthcare, MobiHealth 2023, held in November 29-30, 2023 in Vila Real, Portugal. The 35 full papers of MobiHealth 2023 were carefully selected from 111 submissions and present science and technology aspects in the field of wireless communication, mobile computing and healthcare applications. The conference papers are organized in topical sections on: Medical, communications and networking; Digital imaging and communications in medicine (DICOM). Biomedical, and health informatics; Multimedia e-Health data exchange services. Signal/Data processing and computing for health systems.