This book constitutes the revised selected papers of the 18th EAI International Conference on Mobile Multimedia Communications, MobiMedia 2025, held in Lhasa, China, during August 15-17, 2025. The 26 full papers included in this book were carefully reviewed and selected from 70 submissions. They are organized in topical sections as follows: Algorithms, Architecture, Applications of 5G/6G; Flexible Architecture in AI-Enabled Software-Defined Networks; Wireless Body Area Network (WBAN); Computational Framework and Structure for Big Data. Localization, Positioning and Tracking Techniques; Heterogeneous Data Storage; Multimedia-Based Signal Processing; Mobile Crowdsensing; Real-Time Stream Data Mining; and AI for Communication.