Recently developed modular-multilevel converter (M-MC) has a major attention in the industry and research works which is moving into feasible technology for many medium and high-power applications. M-MCs have been improved by existing power conversion technology in several aspects, including efficiency, modular structure, power quality, transformerless operational capability, fault tolerant and redundancy operations having a low expense, standard components utilisation, high availability, excellent quality of output wave forms. However, as several challenges combined with M-MC topologies, include reduced voltage stress, compact size, and substantially lower semiconductor losses. These attributes the lower operating cost for high-power applications such as distribution systems and high-voltage direct current (HVDC) transmission systems. The main contribution of this study is to bring the scrutiny of M-MC applications and different circuit topologies. These M-MC configurations consist of converter structures with sub-module converters and M-MC family members. In such a way, the M-MC applications are generalised and it results the size and cost halved, reduced conduction and switching losses and increases system reliabilities. Moreover, in each application of M-MC, drawbacks, and advantages have been discussed in detail. This review presents the latest performance of M-MC with respect to the mentioned research areas and new applications.