© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Epitaxially grown nanowires of semiconducting thiophene/phenylene co-oligomers (TPCOs) were prepared by mask-shadowing deposition on a cleaved (001) surface of a potassium chloride (KCl) crystal. Under optical pumping, single nanowires of both unsubstituted (p-type) and cyano-substituted (n-type) TPCOs exhibited axial Fabry–Pérot (F-P) lasing above a threshold fluence which decreased to 11–15 μJ cm−2 with increasing nanowire lengths. Their lying molecular orientation and stacking along the nanowire axis in both TPCOs are suitable for effective light propagation with transverse-electric mode resulting in better lasing performances compared to two-dimensional platelet crystals of TPCOs.