Galacto‐oligosaccharides (GOS), increasingly popular prebiotics, are synthesized by enzymatic conversion of lactose. Among others, the total production costs are significantly influenced by the costly enzyme. Therefore, it was investigated if the reuse and full recovery of the enzyme is feasible, followed by the development of a semi‐continuous process in order to maintain a consistent high GOS yield. As a preliminary step, the enzyme‐catalyzed reaction was recorded within the permissible operating parameters. It was successfully shown that steady high GOS yields can be synthesized semi‐continuously within a filtration plant functioning as an enzymatic membrane reactor.