Magnetotactic bacteria (MTB) generate a membrane‐enclosed subcellular compartment called magnetosome, which contains a biomineralized magnetite or greigite crystal, an inner membrane–derived lipid bilayer membrane, and a set of specifically targeted associated proteins. Magnetosomes are formed by a group of magnetosome‐associated proteins encoded in a genomic region called magnetosome island. Magnetosomes are then arranged in a linear chain–like positioning, and the resulting magnetic dipole of the chain functions as a geomagnetic sensor for magneto‐aerotaxis motility. Recent metagenomic analyses of environmental specimens shed light on the sizable phylogenetical diversity of uncultured MTB at the phylum level. These findings have led to a better understanding of the diversity and conservation of magnetosome‐associated proteins. This review provides an overview of magnetosomes and magnetosome‐associated proteins and introduces recent topics about this fascinating magnetic bacterial organelle.