Mesoporous carbon nitride (MCN) is a fascinating material with enhanced textural properties, tailored morphology and enriched surface functionalities. Hence, it demonstrates promising performance in various applications. Over the years, various methods such as hard template, soft template, template-free, etc. have been adopted toward the preparation of MCN with controlled structural properties. Furthermore, the exciting properties of MCN have been fine-tuned by controlling the morphology and tuning the textural properties and surface functionalities, including the type and amount of nitrogen, via simple adjustment of the precursors, the carbonization temperature and the nature of the structure-directing agents/hard template. Besides these, the integration of conductive carbon, heteroatoms, metal-based materials, organic molecules, etc. was found to not only enhance MCN's performance in the already existing applications but also open up more exciting applications. The present Review begins by providing a general overview of the salient features of MCN, which dictate its performance in the various applications. Then, the Review discusses the trends in the applications of MCN-based material in the areas of electrochemical energy storage and conversion and gas storage in the past decade. The structure-property relationships of MCN-based materials in the above-mentioned applications are also discussed in detail. Emphasis is given to the role of the synthetic approach adopted and the nature of the precursor(s) used toward controlling the textural, morphological properties and chemical composition of MCN-based materials in obtaining the final product with improved performance. Moreover, the effects of modifications of key features of MCN on its electrochemical performance are also discussed. Finally, the current challenges and perspectives are provided, thereby guiding future research in the field of MCN-based materials for electrochemical energy storage and conversion and gas storage.