The morphology and field-effect transistor (FET) characteristics of electrospun (ES) nanofibers prepared from crystalline poly(3-hexylthiophene) (P3HT) and poly(stearyl acrylates) (PSA) or poly(n-lauryl acrylate) (PnLA) blends via the coaxial electrospinning technique are reported. The FET mobility of the 1:0.2 P3HT/PSA blend ES nanofibers is 3.21 x 102 cm2 V1 s1, which is two orders of magnitude higher than that of pure P3HT ES nanofibers (1.92 x 104 cm2 V1 s1). In addition, the FET hole mobilities of the P3HT/PSA blend ES nanofibers using the other ratios are also larger than that the P3HT. The crystalline PSA promotes P3HT to form a more compact structure in the ES nanofibers as evidenced by DSC, leading to the enhanced FET mobility. Similarly, the mobility of P3HT/PnLA (1:0.2) blend ES nanofiber-based FETs also improves to 2.40 x 102 cm2 V1 s1. The strong stretching force and the geometrical confinement associated with the ES process results in oriented P3HT packing, as evidenced by transmission electron microscopy (TEM) and grazing-incidence wide-angle X-ray scattering (GIXS). The P3HT/PSA ES nanofibers form a core-sheath structure and thus the penetration of moisture and oxygen is prevented, enhancing the air stability of FET devices. The study reveals that P3HT blended with crystalline PSA (or PnLA) can fabricate high-performance nanofiber-based FET devices.