This book delves into the fascinating world of iron-based magnetic nanoparticles and focuses primarily on their synthesis. The synthesis of iron-based MNPs is a complex and intricate process that requires a deep understanding of materials science, chemistry, and nanotechnology. Over the years, various methods have been explored and developed to fabricate iron-based MNPs with different sizes, shapes, and compositions. The chapters within this book explore the diverse synthesis methods employed in the creation of iron-based MNPs. From traditional precipitation techniques to sophisticated approaches such as thermal, pyrolysis, vapor deposition, and sonochemical methods, each method is thoroughly examined and discussed. I am profoundly grateful to Dr. N.M. Abdul Khader Jailani, my beloved teacher and well-wisher, for his invaluable guidance and unwavering support throughout my academic journey. His passion for science and dedication to teaching has been a constant source of inspiration for me. It is with great honor and gratitude that I dedicate this book to him, as a testament to his influence on my pursuit of knowledge.