The area of intelligent multimedia involves the real-time computer processing and understanding of perceptual input from speech, textual and visual sources. The present reprint contains the 13 articles accepted and published in the Special Issue "Advanced Mathematical Methods in Intelligent Multimedia: Security and Applications" of the MDPI journal "Mathematics", which cover a wide range of topics connected to the theory, security, and applications of these methods. These topics include, among others, elements from privacy computation, game theory-based models, cloud computing, big data, location privacy, artificial intelligence, reputation system, differential privacy, reversible data hiding, blockchain, etc. It is hoped that the reprint will be interesting and useful for those working in the area of intelligent multimedia, security systems and privacy methods, as well as for those with the proper mathematical background who are willing to become familiar with recent advances of secure mathematics, which has nowadays entered into almost all sectors of human life and activity.