In the past decades, interest for new catalysts and new catalytic reactions increases greatly due to their large applications in several domains such as pharmaceutical and chemical industries. New catalysts were described for an increasing number of organics reactions. Nevertheless, most of the homogenous catalysts are difficult to adapt to industrial process due to separation and regeneration problems. Moreover, though highly efficient, most of the catalysts are containing noble or toxic metals and so new protocols more economically and environmentally friendly need to be developed. Recently, more attention has been paid to the use of nanomaterials as support. In fact, due to their unique properties and their enhanced surface volume ratio putting them at the frontier between heterogeneous and homogeneous catalysis, nanomaterials are quickly becoming the support of choice for catalysis applications. Among them, magnetic nanoparticles appear as an ultimate nanosupport due to their easiness of recovery owing to their magnetic properties. The simple use of an external magnet could afford the rapid recovery of the catalyst without the need of filtration or centrifugation. The interest in catalysis using magnetic nanoparticles as a support is increasing dramatically and several nanomagnetic catalysts were proposed recently. In this chapter, we present the fundamentals of the magnetic nanoparticles synthesis and an overview of the preparation of nanomagnetic catalysts focusing on the NPs coating. Literature examples of the various types of nanomagnetic catalyst, the different applications in chemical synthesis as well as limitations and recent outlooks for these new objects are described.