This paper describes a method based on electrospinning using a novel dual-spinneret to fabricate Janus-type nanofiber with thermoelectric p-n heterostructure. Co3O4/TiO2 composite nanofibers were synthesized after calcining the precursor composite fibers with Janus-type morphology, as confirmed by X-ray diffraction and transmission electron microscopy. Scanning electron microscopy images show that the diameter of the Co3O4/TiO2 composite ceramic fiber is in the range of 300-1000 nm, the surface of both precursor and ceramic fibers are smooth, and the diameter is uniform across their length. Energy dispersive spectroscopy demonstrated that the Co3O4/TiO2 composite nanofibers are formed by combining n-type TiO2 in one side with p-type Co3O4 in the other side, with the p-n junction formed at the interface of the Janus-type nanofiber. The novel Janus-type structure could find a variety of applications as a p-n junction in nanoscale thermoelectric devices.