Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is of great interest as a promising metal-free electrode material for future electronic devices. Several printing techniques have been developed to generate PEDOT:PSS patterns. In this study, we introduced a silicon-based hardener into PEDOT:PSS composites to prepare conductive ink for the purpose of fabricating solvent-resistant PEDOT:PSS composite patterns. Electrohydrodynamic (EHD) jet printing enabled the direct patterning of PEDOT:PSS and hardener composites that exhibited improved electrical conductivity and solvent resistance, which are advantageous properties for efficient charge injection when semiconductor materials are coated onto pre-deposited PEDOT:PSS composite electrodes. By using EHD jet printed PEDOT:PSS composites as source and drain electrodes, bottom-gate-bottom-contact organic thin-film transistors (OTFTs) were fabricated. The resulting OTFTs with PEDOT:PSS and hardener composite electrodes exhibited superior electrical performance compared to OTFTs with electrodes without hardener. Finally, OTFTs with both EHD jet printed electrodes and semiconductors were fabricated and analyzed.