The increasing demand for flexible electromechanical devices with superior stretchability, durability, thermal stability and sensitivity has driven the development of new smart functional materials to replace conventional semiconductors. This study utilises combining electrospinning and in situ polymerisation to fabricate four types of thermoplastic polyurethane/polyaniline (TPU/ PANI) nanofibrous membranes with varied fibre orientation and multiwalled carbon nanotubes (MWCNTs) incorporation. The combined effects of material composition and fibre alignment on strain-sensing performance were systematically explored. All membranes exhibited stable, symmetric ohmic behaviour under strain, with current decreasing as strain increased. Remarkable repeatability and stability were observed in cyclic current–time tests. MWCNTs addition significantly enhanced conductivity, with aligned fibres further boosting performance. Gauge factor (GF) measurements revealed that aligned TPU/PANI mats had GFs of 7 (0%–18% strain) and 14.3 (18%–40%), while aligned TPU/MWCNTs/PANI mats had GFs of 5.2 (0%–13%) and 7.3 (13%– 40%). Random TPU/PANI mats showed GFs of 13.9 (0%–11%) and 23.3 (11%–40%) and random TPU/MWCNTs/PANI mats had GFs of 13.9 (0%–19%) and 24.7 (19%–40%). Each configuration demonstrated suitability for specific applications, with random TPU/MWCNT/PANI mats exhibiting the best overall performance. This research provides critical insights into optimising flexible strain sensors by tuning both material composition and fibre orientation.