By cofactor redesign, self-sufficient monooxygenases could be prepared. Tight binding of N-alkylated flavins to riboflavin-binding protein results in the creation of artificial flavoenzymes capable of H(2)O(2)-driven enantioselective sulfoxidations. By altering the flavin structure, opposite enantioselectivities could be achieved, in accordance with the binding mode predicted by in silico flavin-protein docking of the unnatural flavin cofactors. The study shows that cofactor redesign is a viable approach to create artificial flavoenzymes with unprecedented activities.