Flow chemistry has many advantages over batch synthesis of organic small-molecules in terms of environmental compatibility, safety and synthetic efficiency especially when scale-up is considered. However, its application in manufacturing active pharmaceutical ingredients (APIs) is still rare due to the complexity involved with operating a multistep continuous reaction sequence. As the demonstration of an alternative approach in steroid chemistry, herein, we report the first 10-step chemo-biocatalytic continuous flow asymmetric synthesis of cyproterone acetate (4) in which 10 transformations are combined into a telescoped flow linear sequence from commercially available 4-androstene-3, 17-dione (11). This integrated one-flow synthesis features an engineered 3-ketosteroid-Δ1-dehydrogenase (ReM2)-catalyzed Δ1-dehydrogenation to form the C1, C2-double bond of the A ring, a substrate-controlled Co-catalyzed Mukaiyama hydration of Δ1, 4, 16-triene-3, 20-dione 9 to forge the crucial chiral C17α-OH group of the D ring with excellent stereoselectivity, and a rapid flow Corey-Chaykovsky cyclopropanation of 17α-hydroxy-Δ1, 4, 6-triene-3-one-20-ketal 7 to build the cyclopropyl core of the A ring. By strategic use of these three key reactions and fully continuous-flow operations, cyproterone acetate (4) was produced in an overall yield of 9.65% in 3 h of total reaction time, this is the shortest route to this steroid, and the highest total number of chemical transformation performance in any other continuous-flow synthesis reported to date. Also included is the Ni-catalyzed batch-mode nucleophilic cyclopropanation using DCM as methylene source for the formation of disubstituted three-membered ring on A ring in steroids with excellent chemo-regio-diastereoselectivity.