The growing presence of water contaminants, such as organic pollutants and heavy metals, poses substantial environmental, and public health risks due to their toxicity and carcinogenic nature. Magnetic nanocomposites have emerged as effective materials for wastewater treatment, offering advantages like high surface area, magnetic responsiveness, and versatile functionalization capabilities. This chapter explores the synthesis techniques, such as co-precipitation, sol–gel, and green synthesis approaches, emphasizing their role in tailoring nanocomposites for enhanced performance and applications of magnetic nanocomposites in removing toxic contaminants from wastewater. Adsorption, photocatalytic degradation, and ion-exchange mechanisms are also highlighted in this chapter mentioning their effectiveness in removing toxic contaminants. Furthermore, it addresses the challenges associated with their practical application, including material stability, reusability, and potential environmental risks.