This book constitutes the refereed proceedings of the 4th Multidisciplinary International Symposium on Disinformation in Open Online Media, MISDOOM 2022, held in October 2022. The 7 full papers and 3 short papers were carefully reviewed and selected from 17 full/short paper submissions. The papers focus on health and climate change misinformation, social bots and comment moderation, information seeking and diffusion, misinformation detection, and user perception-based trust models.