Biopolymer-coated magnetic nanoparticles have emerged as promising materials with diverse applications. These nanoparticles, typically composed of a magnetic core, typically iron oxide or other magnetic materials coated with biocompatible polymers, exhibit unique properties such as magnetic responsiveness, biocompatibility, and tunable surface chemistry. This chapter explores the synthesis, characterization, and applications of biopolymer-coated magnetic nanoparticles (MNPs). Biopolymers, being eco-friendly and biocompatible, have gained significant interest for coating MNPs, imparting them with enhanced stability, functionality, and biocompatibility. The chapter discusses various biopolymers used for coating MNPs, their synthesis techniques and the influence of biopolymer coatings on the magnetic properties of MNPs. Furthermore, the chapter highlights the diverse applications of biopolymer-coated MNPs across biomedical, environmental fields, drug delivery and biosensing.