AbstractMixed‐valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room‐temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule‐based materials can combine physical and chemical properties associated with molecular‐scale building blocks, their successful integration into real devices depends primarily on higher‐order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced‐dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is built up by means of a modified Langmuir–Blodgett technique, where the PBA is synthesized from precursors in a self‐limited reaction on a clay mineral surface. The focus of this work is understanding the magnetic properties of the PBAs in different periodic, low‐dimensional arrangements, and the influence of the “on surface” synthesis on the final properties and dimensionality of the system.