Cardiac electrophysiology, particularly intracellular action potential (iAP) recordings, is vital for advancing the understanding and treatment of cardiovascular diseases. In this work, we present a 3D-printed flexible nanosilver electrode array (FlexNEA) that enables simple and efficient circuit fabrication within several minutes using a multimaterial electric-field-driven (EFD) micro-jet 3D printing strategy and achieves over 99% success rates in intracellular access through electroporation. The NEA with flexible property creates an enhanced cell-electrode coupling, with the cardiomyocyte membrane wrapping tightly around the nanosilver electrode, leading to superior signal quality in contrast to the conventional planar electrodes. The 3D-printed FlexNEA enables stable, high-fidelity intracellular recordings by multiple consecutive biosafe electroporations over a short or long period of time. Moreover, the platform exhibits a powerful drug screening function by accurately detecting drug-induced iAP alterations, providing a precise and quantitative assessment of ion-channel drug effects. In summary, the 3D-printed FlexNEA device and integrated biosensing-regulating platform present a significant advance in the high-fidelity intracellular recording technology of cardiac electrophysiology. The platform advances the development of low-cost, biocompatible NEA systems for preclinical research in the cardiology and pharmacology fields.