During the past decades biocatalytic reactions became a powerful alternative to conventional chemical synthetic pathways for the synthesis of valuable compounds. Such bio-based processes are also considered as powerful tools towards environmentally friendly synthetic processes since often mild reaction conditions are applied. However, a careful selection of reaction conditions must be taken into account, as biocatalytic processes can be limited by reaction-specific complications such as undesired chemical side reactions and unfavorable reaction equilibria. These issues cannot be solved by any optimization of the biocatalyst itself and alternative strategies to overcome such issues need to be developed within process development. We present the integrated use of selective crystallization as a promising process concept for solving this problem, specifically directly within the biocatalytic reaction (solution). This unusual technique enables the direct removal of the desired reactant, typically but not necessarily the targeted product, which can be regarded as an option for in-situ product removal to achieve higher (apparent) product concentrations. The concept essentially leads to a heterogenization of the biocatalytic reaction medium itself and can be considered as an integrated or subsequent downstream processing step.