Skeletal metastatic disease accounts for significant overall morbidity in cancer patients. Accurate and accessible imaging forms an integral part of the investigation for patients with suspected or known skeletal metastatic disease; it is considered indispensable in making appropriate oncological treatment decisions. Magnetic resonance imaging (MRI) is a contemporary imaging modality that provides excellent spatial and contrast resolution for bone and soft tissues. Therefore, it is particularly useful for imaging patients suffering from metastatic skeletal disease. This review provides a fundamental overview of the physics and image generation of MRI. The most commonly used MRI sequences in the investigation of metastatic skeletal disease are also discussed. Additionally, a review of the pathophysiological basis of metastatic bone disease is presented, along with an introduction to the interpretation of MRI sequences obtained for metastatic bone disease. Finally, the strengths and drawbacks of MRI are considered in comparison to alternative imaging modalities for the investigation of this common and important oncological complication.