A major challenge in carbon. hydrogen (C-H) bond functionalization is to have the catalyst control precisely where a reaction takes place. In this study, we report engineered cytochrome P450 enzymes that perform unprecedented enantioselective C-H amidation reactions and control the site selectivity to divergently construct beta-, gamma-, and delta-lactams, completely overruling the inherent reactivities of the C-H bonds. The enzymes, expressed in Escherichia coli cells, accomplish this abiological carbon. nitrogen bond formation via reactive iron-bound carbonyl nitrenes generated from nature-inspired acyl-protected hydroxamate precursors. This transformation is exceptionally efficient (up to 1,020,000 total turnovers) and selective (up to 25:1 regioselectivity and 97%, please refer to compound 2v enantiomeric excess), and can be performed easily on preparative scale.