Green and selective oxidation methodsa re highly desired in chemical synthesisa nd manufacturing. In this work, we have developedabiocatalytic method for the regio-and stereoselective oxidation of styrene derivatives into arylacetic and( S)-2-arylpropionic acids via ao ne-pot epoxidation-isomerization-oxidation sequence.T his was done via the engineering of Escherichia coli (StyABC-EcALDH)c oexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI) and aldehyde dehydrogenase (EcALDH)a sa na ctive and easily available wholecell catalyst. Regioselective oxidation of styrene and 11 substituted styrenes using the E. coli cells wasperformed in ao ne-pot set-up,p roducing 12 phenylacetic acids in bothh igh conversion and high yield. Engineering of E. coli (StyABC-ADH9v1) coexpressing SMO,S OI andA DH9v1 (a mutated alcohol dehydrogenase) led to biocatalystsc apable of regio-and stereoselective oxidation of a-methylstyrene derivatives to the corresponding chiral acids.O ne-pot asymmetric synthesis of 4( S)-2-arylpropionic acids was achieved in good conversion and excellent ee with the E. coli cells.T his is an ew type of asymmetric alkene oxidation to give chiral acids with no chemical counterpart thus far. Thec ascade bio-oxidation operates under mild conditions,u ses molecular oxygen, exhibitsv ery high regio-and enantioselectivity,a nd gives high conversion, thus providing ag reena nd efficientm ethod for the synthesiso fa rylacetic acids and (S)-2-arylpropionic acids directly from easily available styrenes.