In this chapter, the state of art of the functional magnetic materials based on metal formate frameworks (MFFs), mainly developed in the past decade, is provided. These materials, belonging to a relatively small yet fundamentally important class of metal‐organic frameworks (MOFs), possess various structures and interesting properties. The binary or ternary dense MFFs display complicated structures and various magnetic behaviors though their constituents are simple. MFFs with ammonium components exhibited abundant and interesting magnetism, di‐/ferro‐/antiferroelectric and mechanical properties, structural phase transitions, and critical phenomena triggered by various order–disorder transitions of ammoniums, and the chirality, as well as the possible combinations such as multiferroics. These ammonium MFFs mimic the traditional inorganic materials such as perovskite, niccolite, and diamond. The porous diamondoid MFFs of [M
3
(HCOO)
6
] possess a wide spectrum of gas and guest inclusion behaviors. They thus show guest‐modulated magnetism, guest‐induced chirality, and guest‐based electric polarization. Mixing formate with coligands has provided MFFs with not only beautiful and fantastic structures but also interesting and appealing magnetic properties and others. It has been demonstrated that the formate, being the smallest and simple carboxylate, cheap and less toxic thus more biocompatible and environment‐friendly, and having been more or less ignored before, now comes back to our sight and awareness with its important role, having been verified, in the construction of promising MOF materials, and provides new materials with interesting properties.