Microwave irradiation, being an electromagnetic wave, facilitates volumetric heating through various dielectric heating modes such as dipolar polarization and ionic conduction. In this review, an attempt has been made to critically discuss various principles associated with microwave–material interactions. The review has given particular importance to recent developments in microwave-assisted material synthesis and processing of various materials such as metals, ceramics, polymers, nanoparticles, and food materials. The microwave method has various advantages over conventional heating methods in terms of reaction kinetics, product uniformity, and energy efficiency. The review also critically discusses some of the challenges faced by microwave–material interactions and how they can be addressed by adopting new strategies, such as hybrid heating and reactor innovations. In addition, future research directions have also been outlined to take microwave technologies to new heights in material processing.