Organic electrochemical transistors (OECTs) have garnered significant interest due to their ability to facilitate both ionic and electronic transport. A large proportion of research efforts thus far have focused on investigating high-performance materials that can serve as mixed ion doping and charge transport layers. However, relatively less attention has been given to the gate-electrode materials, which play a critical role in controlling operational voltage, redox processes, and stability, especially in the context of semiconductor-based OECTs working in accumulation mode. Moreover, the demand for planarity and flexibility in modern bioelectronic devices presents significant challenges for the commonly used Ag/AgCl electrodes in OECTs. Herein, we report the construction of high-performance accumulation-mode OECTs by utilizing a gate electrode made of three-dimensional (3D)-printed graphene oxide. The 3D-printed graphene oxide electrode incorporating one-dimensional (1D) carbon nanotubes, is directly printed using an aqueous-based ink and showcases exceptional mechanical flexibility and porosity properties, enabling high-throughput preparation for both top gates and integrated planar architecture, as well as fast ion/charge transport. OECTs with high performance comparable to that of Ag/AgCl-gated OECTs are thus achieved and present promising feasibility for electrocardiograph (ECG) signal recording. This provides a promising choice for the application of flexible bioelectronics in medical care and neurological recording.