In the past few years, three‐dimensional self‐supporting porous magnetic assemblies (3D‐SPMAs) have emerged as a new research area in materials science because of their combined features of three‐dimensional self‐supporting porous assemblies (3D‐SPAs) and magnetic materials. Due to these attributes, 3D‐SPMAs gain numerous tempting properties such as magnetism‐induced actuating, magnetic shape memory effects, and alternative magnetic field (AMF) induced heat generation, showcasing huge potential in diverse applications stretching over water remediation, actuators, biomedical therapy, etc. Especially, 3D‐SPMAs displayed eminent potential in water remediation for their large processing capacity, remote controllability, and magnetic‐field‐mediated wettability. With the rising interest in 3D‐SPAs, the increasing understanding of magnetic materials, and the flourish of materials preparation technique, an upsurge has appeared in 3D‐SPMAs and thus managing them a class of emerging and promising functional materials. However, currently there are rarely review papers concerning 3D‐SPMAs. In this light, this review aims to express a comprehensive overview of this young field and fuel further innovations for preparation methods and practical applications of 3D‐SPMAs. The focus is placed on the synthetic strategies and applications especially in water remediation. The potential opportunities and challenges are also discussed.