Abstract The use of selected engineered galactose oxidase (GOase) variants for the oxidation of amino alcohols to aldehydes under mild conditions in aqueous systems is reported. GOase variant F 2 catalyses the regioselective oxidation of N ‐carbobenzyloxy (Cbz)‐protected 3‐amino‐1,2‐propanediol to the corresponding α‐hydroxyaldehyde which was then used in an aldolase reaction. Another variant, M 3–5 , was found to exhibit activity towards free and N ‐Cbz‐protected aliphatic and aromatic amino alcohols allowing the synthesis of lactams such as 3,4‐dihydronaphthalen‐1(2 H )‐one, 2‐pyrrolidone and valerolactam in one‐pot tandem reactions with xanthine dehydrogenase (XDH) or aldehyde oxidase (PaoABC).