The three-volume proceedings set LNCS 13655,13656 and 13657 constitutes the refereed proceedings of the 4th International Conference on Machine Learning for Cyber Security, ML4CS 2022, which taking place during December 2-4, 2022, held in Guangzhou, China. The 100 full papers and 46 short papers were included in these proceedings were carefully reviewed and selected from 367 submissions.