This three-volume set in LNCS constitutes the refereed proceedings of the 30th Australasian Conference on Information Security and Privacy, ACISP 2025, held in Wollongong, NSW, Australia, during July 14–16, 2025. The 54 full papers, 6 short papers and 1 invited paper included in this book were carefully reviewed andselected from 181 submissions. They were organized in topical sections as follows: symmetric-key cryptography and cryptanalysis; public-key encryption; digital signatures and zero knowledge; cryptographic protocols and blockchain; post-quantum cryptography; homomorphic encryption and applications; cryptographic foundations and number theory; privacy enhancing technologies; AI security and privacy; system security.