Due to the feasibility of running continuous enzymatic reaction and product separation in a single operation, enzymatic membrane reactors (EMRs) are increasingly applied in the areas of biotechnology, (bio)chemistry, agro-food, and energy. By the use of different membrane cut-offs, enhanced separation selectivity can be obtained during the production of fine chemicals which vary in molecular sizes. Within this review, available designs of EMR are discussed based on membrane functions, hydrodynamic and filtration characteristics. Further, various applications of EMRs are outlined and tabulated, especially in the agro-food, pharmaceutical, environmental, and energy sectors. As a well-known problem in membrane technology, fouling and its circumventions especially in size-exclusion EMR are also critically discussed. Several own and literature results are presented to give overall concepts of EMR operation and used to describe future research trends within the scope of this reactor design.