New donor–acceptor conjugated copolymer, PSeDPP, consisting of selenophene (Se) and 3,6-dithiophen-2-yl-2,5-dialkylpyrrolo[3,4-c]pyrrole-1,4-dione (DPP), was developed for high performance ambipolar field-effect transistors (FETs) and nonvolatile memory applications. The maximum absorption peak and optical band gap of PSeDPP thin film were observed at 849 nm and 1.29 eV, respectively, indicating the strong intramolecular and intermolecular charge transfer. The polymer crystallinity and FET mobility was significantly enhanced as increasing the solvent boiling point and thermal treatment based on the results from four processing solvents of chloroform, chlorobenzene, o-dichlorobenzene and 1,2,4-trichlorobenzene, as evidenced by TEM, XRD, and AFM. The PSeDPP-based FET processed from1,2,4-trichlorobenzene exhibited a dense nanofiber morphology with lamellar chain packing, leading to the relatively high hole and electron mobility up to 1.62 and 0.14 cm² V⁻¹ s⁻¹, respectively. PSeDPP was also found to exhibit the first transistor memory characteristics for ambipolar conjugated polymers. The retention time of the FET-based nonvolatile memory devices could maintain the high- and low-conductance states longer than 10⁴ s, and the on-off current ratios of 10³–10⁴ at the read voltage of 0 V. These results revealed that PSeDPP had potential applications for flexible electronic device applications.