This book constitutes the refereed proceedings of the 23rd International Symposium on Automated Technology for Verification and Analysis, ATVA 2025, held in Bengaluru, India, from October 27–31, 2025.The 17 full papers and 4 short papers included in the proceedings were carefully reviewed and selected from 59 submissions. They were organized in topical sections as follows: Automata and temporal logic; games and controller synthesis; monitoring and runtime verification; probabilistic verification and quantum computing; learning; hybrid and dynamical systems; and verification.