Rechargeable magnesium batteries (RMBs) have been considered as one of the most viable battery chemistries amongst the “post” lithium‐ion battery (LIB) technologies owing to their high volumetric capacity and the natural abundance of their key elements. The fundamental properties of Mg‐ion conducting electrolytes are of essence to regulate the overall performance of RMBs. In this Review, the basic electrochemistry of Mg‐ion conducting electrolytes batteries is discussed and compared to that of the Li‐ion conducting electrolytes, and a comprehensive overview of the development of different Mg‐ion conducting electrolytes is provided. In addition, the remaining challenges and possible solutions for future research are intensively discussed. The present work is expected to give an impetus to inspire the discovery of key electrolytes and thereby improve the electrochemical performances of RMBs and other related emerging battery technologies. The fundamental physical and electrochemical properties of Mg‐ion conducting electrolytes are scrutinized with particular attention paid to the similarity and difference between Mg‐ion and the popular Li‐ion based electrolytes. The Review was written with the intention of accelerating the development of sustainable and high‐performance battery technologies.