Efficient bi-enzymatic cascades combining aldolases and α-transaminases were designed for the synthesis of γ-hydroxy-α-amino acids. These recycling cascades provide high stereoselectivity, atom economy, and an equilibrium shift of the transamination. L-syn or anti-4-hydroxyglutamic acid and D-anti-4,5-dihydroxynorvaline were thus prepared in 83–95% yield in one step from simple substrates.