Microbial electrochemical systems use the electrochemical interaction between microorganisms and electrode surfaces to convert chemical energy into electrical energy, offering promising technologies for wastewater treatment, bioremediation, and biofuel production. Recently, research has been focusing increasingly on the development of microbial electrochemical sensors as biosensing platforms. Microbial electrochemical sensors are a type of microbial electrochemical technology (MET) capable of detecting information through anodic or cathodic electroactive microorganisms and/or biofilms. In this work, we review and summarize recent advances in the design of microbial electrochemical sensing approaches with an overview and specific discussion of anodic and cathodic microbial electrochemical sensor devices, highlighting both advantages and disadvantages. Particular emphasis is given to current trends and strategies in designing low-cost, convenient, efficient, and high-performance METs with diverse biosensing applications, including toxicity monitoring, pathogen detection, corrosion monitoring, as well as measuring biological oxygen demand, oxygen demand and dissolved oxygen. The conclusion provides perspectives for understanding the shortcomings in the design, development status, and sensing applications of microbial electrochemical platforms. Namely, we discuss key challenges that limit the practical implementation of METs for sensing purposes and explore potential solutions, necessary developments, and improvements in the field.